I noticed the beginning of the downfall of Blizzard when the first WoW expansion (The Burning Crusade) released in 2007. Activision bought Blizzard shortly after in 2008. I can't describe it perfectly, but in TBC Blizzard began making some pretty stupid decisions that didn't make sense. Well, it made sense for making money, but not for making a better game. It was small mistakes at first, but over time they got bigger and more blatant. Even though Wrath of the Lich King was arguably the most loved and successful WoW expansion by fans, it was obvious by then that Blizzard was only making changes to make more money, to keep the subscribers in the hamster wheel. Greed can only sustain a company for so long until it collapses. We're seeing the late stages of it in Blizzard now. It's hilarious too, that greed started their downfall, and now they're essentially admitting "I hate money". Diversity and inclusion pairs with gamers as much as oil and water.
The focus on arena in TBC destroyed guild cohesion. It was much easier to get a 2-5 man team and grind pvp than a 20-40 man raid.
I get they don't want to spend much effort on content only a few no-lifes will ever see but just the existence of "aspirational" content made the game much more interesting.
The "honor" system was beyond retarded and made pvp servers close to unplayable. I know its all "thats world pvp" but in-game rewards for ganking was a really bad idea.
Cross server BGs did decrease the queues but also destroyed the character of the servers, preventing fun rivalries.
I did like the arenas in TBC but I understand were you are coming from, it splintered guilds and made raiding harder for some guild but it was still very much enjoyable.
Maybe it it youth or something but I loved TBC.
TBC was probably peak WoW despite Wrath being so widely acclaimed.
As many point out Wrath only really had a few good selling points.
Big bad was a huge lore character and unlike with Illidan in TBC you had the Lich King pop up several times from the Wrath starting zones 'til ICC, in part because of how little players saw Illidan in TBC despite also being a huge lore character as well as continuing the Caverns of Time time-traveling journey by adding in the Culling of Stratholme which let long time players relive the Warcraft 3: Frozen Throne story there.
Ulduar. A lot of new mechanics were added in Wrath in general such as "Vehicles" which the players could "first" experience during the Death Knight starter chain when controlling a ship cannon and bombarding a beach of religious zealots. While the Malygos fight had a vehicle phase at the very end [that could at least be practiced through the Aces High quest near the raid entrance], it was still only a straightforward 3 button mash fest. Ulduar started with the Leviathan Gauntlet and later boss fight using several different vehicle types. It also was the first of the raids to feature "Hard modes" since the previous content was the revamped Naxx that everyone could have run in TBC even after Vanilla ended, the Sartharion single dragon boss encounter similar to Onyxia, and the Malygos raid so tier 7 wasn't really that creative. Tier 8/Ulduar on the other hand meant a lot of both new lore and content since it dealt with the Old Gods that hasn't been addressed since the AQ20 and AQ40 raids.
Wrath was also a step back to non welfare Legendaries as TBC Warglaives and Thori'dal were both Rogue drops simply very low RNG drops. The Ulduar healing mace and later ICC 2h axe had long crafting chains that also required certain raid boss fights to be done in special ways.
However also as pointed out it added some of the worst features to ever happen in the game.
LFG which later added LFR [Looking for Retards Raid] in Cata, and the wow store with various mounts and other aesthetics that were often several times over a monthly sub price.
TBC meanwhile dropped the ball by underusing Illidan as well as writing him poorly enough that Legion retconned his actions to paint him as an anti-hero.
Karazhan was an incredible introductory raid despite it only being a 10man.
T5 content SSC/TK were a good mix of easy [Lurker/Loot Below + Void/Loot Reaver] to extremely difficult [Vashj + Kael'Thas] content and attunements were still a thing throughout the expansion although this itself was often a gripe. Note that's only the attunement for t4. T5 required you to do that for every character you had so if someone rerolled they needed to that all over again every time.
T6 content dealt with Mount Hyjal and Black Temple, both significant lore locations which helped hype them up, and in the case of the former dealt with Warcraft 3 history as was often the case with the time-traveling dungeons and raids.
Black Temple was effectively the crowning point of TBC however because Illidan had been so absent his eventual defeat felt empty to many and Wrath was still months away so additional content in the forms of the Isle of Quel'Danas and Sunwell were brought in along with the achievement system which served as a carrot for all the completionists to go back and do content they had probably done dozens of time before.
Also items and crafting were kinda broken in TBC since even just the regular non raid crafts were at times on par with T5 gear and the later Sunwell recipe drops were so OP players not only dropped existing professions that they may have had since Vanilla but were able to use some of those items well into Wrath. One of the best tanking trinkets in game for Avoidance/Dodge was still a Vanilla drop from Blackwing Lair. While it's understandable for things like the Vanilla Legendaries to still be competitive in TBC the fact non t3 items weren't challenged by TBC content highlights a lack of creative design when filling in itemisation spots. Additionally there was a Chinese guild that managed to clear all of TBC still wearing their full t3 because the full 8/8 set [back when 8/8 sets were still a thing] was that powerful compared to the new content despite the jokes about replacing it all with your very first quest hand in. Set bonuses would very often piss all over stat increases when they could fundamentally change something like a caster's mana budget.
Edit: Visual depiction of Vanilla and TBC attunements. Section on the left is Vanilla with the red boxes showing the raid content. Molten Core.MC was tier 1. Blackwing Lair/BWL was tier 2. Naxx was tier 3. The other red boxes were either one off world bosses in the cases of Kruul, Azuregos, Lethon/Ysondre/Emeriss/Taerar, or the AQ raids which served as a sort of tier 2.5. Back in vanilla attunemts and gear were a lot less forgiving if you were missing something. You NEEDED frost res gear for Naxx or a lot of bosses would wipe your group quickly. You NEEDED nature res gear for AQ raids or similar deaths would happen. All the while various raid bosses could be parts of the Legendary crafting quests which would involve weekly farming on the chance an item might drop such as the 40 Atiesh staff fragments which would then still need both the final AQ40 and Naxx bosses killed for the remaining two missing parts. At that point you had killed everything in the game already but still needed to keep farming it to make one of the best caster weapons in the game at the time.
TBC attunement was... extensive as shown on the right side. Everything needed done in order to enter Hyjal before the attunements were lifted later in the expansion. While rerolling could be sped up by having established t6 raiders boosting a new character it still meant having to run ALL OF THAT every time someone might have needed to replace a character. Because of this raid groups could be very protective about their members as attuning someone only for them to leave and join another group was a massive pain and waste of time and resources. And it happened.
Blizzard has been dead to me since Startcraft 2 required online login to play the game purely in single player.
I noticed the beginning of the downfall of Blizzard when the first WoW expansion (The Burning Crusade) released in 2007. Activision bought Blizzard shortly after in 2008. I can't describe it perfectly, but in TBC Blizzard began making some pretty stupid decisions that didn't make sense. Well, it made sense for making money, but not for making a better game. It was small mistakes at first, but over time they got bigger and more blatant. Even though Wrath of the Lich King was arguably the most loved and successful WoW expansion by fans, it was obvious by then that Blizzard was only making changes to make more money, to keep the subscribers in the hamster wheel. Greed can only sustain a company for so long until it collapses. We're seeing the late stages of it in Blizzard now. It's hilarious too, that greed started their downfall, and now they're essentially admitting "I hate money". Diversity and inclusion pairs with gamers as much as oil and water.
The focus on arena in TBC destroyed guild cohesion. It was much easier to get a 2-5 man team and grind pvp than a 20-40 man raid.
I get they don't want to spend much effort on content only a few no-lifes will ever see but just the existence of "aspirational" content made the game much more interesting.
The "honor" system was beyond retarded and made pvp servers close to unplayable. I know its all "thats world pvp" but in-game rewards for ganking was a really bad idea.
Cross server BGs did decrease the queues but also destroyed the character of the servers, preventing fun rivalries.
I did like the arenas in TBC but I understand were you are coming from, it splintered guilds and made raiding harder for some guild but it was still very much enjoyable. Maybe it it youth or something but I loved TBC.
TBC was probably peak WoW despite Wrath being so widely acclaimed.
As many point out Wrath only really had a few good selling points.
Big bad was a huge lore character and unlike with Illidan in TBC you had the Lich King pop up several times from the Wrath starting zones 'til ICC, in part because of how little players saw Illidan in TBC despite also being a huge lore character as well as continuing the Caverns of Time time-traveling journey by adding in the Culling of Stratholme which let long time players relive the Warcraft 3: Frozen Throne story there.
Ulduar. A lot of new mechanics were added in Wrath in general such as "Vehicles" which the players could "first" experience during the Death Knight starter chain when controlling a ship cannon and bombarding a beach of religious zealots. While the Malygos fight had a vehicle phase at the very end [that could at least be practiced through the Aces High quest near the raid entrance], it was still only a straightforward 3 button mash fest. Ulduar started with the Leviathan Gauntlet and later boss fight using several different vehicle types. It also was the first of the raids to feature "Hard modes" since the previous content was the revamped Naxx that everyone could have run in TBC even after Vanilla ended, the Sartharion single dragon boss encounter similar to Onyxia, and the Malygos raid so tier 7 wasn't really that creative. Tier 8/Ulduar on the other hand meant a lot of both new lore and content since it dealt with the Old Gods that hasn't been addressed since the AQ20 and AQ40 raids.
Wrath was also a step back to non welfare Legendaries as TBC Warglaives and Thori'dal were both
Rogue dropssimply very low RNG drops. The Ulduar healing mace and later ICC 2h axe had long crafting chains that also required certain raid boss fights to be done in special ways.However also as pointed out it added some of the worst features to ever happen in the game.
LFG which later added LFR [Looking for
RetardsRaid] in Cata, and the wow store with various mounts and other aesthetics that were often several times over a monthly sub price.TBC meanwhile dropped the ball by underusing Illidan as well as writing him poorly enough that Legion retconned his actions to paint him as an anti-hero.
Karazhan was an incredible introductory raid despite it only being a 10man.
T5 content SSC/TK were a good mix of easy [Lurker/Loot Below + Void/Loot Reaver] to extremely difficult [Vashj + Kael'Thas] content and attunements were still a thing throughout the expansion although this itself was often a gripe. Note that's only the attunement for t4. T5 required you to do that for every character you had so if someone rerolled they needed to that all over again every time.
T6 content dealt with Mount Hyjal and Black Temple, both significant lore locations which helped hype them up, and in the case of the former dealt with Warcraft 3 history as was often the case with the time-traveling dungeons and raids.
Black Temple was effectively the crowning point of TBC however because Illidan had been so absent his eventual defeat felt empty to many and Wrath was still months away so additional content in the forms of the Isle of Quel'Danas and Sunwell were brought in along with the achievement system which served as a carrot for all the completionists to go back and do content they had probably done dozens of time before.
Also items and crafting were kinda broken in TBC since even just the regular non raid crafts were at times on par with T5 gear and the later Sunwell recipe drops were so OP players not only dropped existing professions that they may have had since Vanilla but were able to use some of those items well into Wrath. One of the best tanking trinkets in game for Avoidance/Dodge was still a Vanilla drop from Blackwing Lair. While it's understandable for things like the Vanilla Legendaries to still be competitive in TBC the fact non t3 items weren't challenged by TBC content highlights a lack of creative design when filling in itemisation spots. Additionally there was a Chinese guild that managed to clear all of TBC still wearing their full t3 because the full 8/8 set [back when 8/8 sets were still a thing] was that powerful compared to the new content despite the jokes about replacing it all with your very first quest hand in. Set bonuses would very often piss all over stat increases when they could fundamentally change something like a caster's mana budget.
Edit: Visual depiction of Vanilla and TBC attunements. Section on the left is Vanilla with the red boxes showing the raid content. Molten Core.MC was tier 1. Blackwing Lair/BWL was tier 2. Naxx was tier 3. The other red boxes were either one off world bosses in the cases of Kruul, Azuregos, Lethon/Ysondre/Emeriss/Taerar, or the AQ raids which served as a sort of tier 2.5. Back in vanilla attunemts and gear were a lot less forgiving if you were missing something. You NEEDED frost res gear for Naxx or a lot of bosses would wipe your group quickly. You NEEDED nature res gear for AQ raids or similar deaths would happen. All the while various raid bosses could be parts of the Legendary crafting quests which would involve weekly farming on the chance an item might drop such as the 40 Atiesh staff fragments which would then still need both the final AQ40 and Naxx bosses killed for the remaining two missing parts. At that point you had killed everything in the game already but still needed to keep farming it to make one of the best caster weapons in the game at the time.
TBC attunement was... extensive as shown on the right side. Everything needed done in order to enter Hyjal before the attunements were lifted later in the expansion. While rerolling could be sped up by having established t6 raiders boosting a new character it still meant having to run ALL OF THAT every time someone might have needed to replace a character. Because of this raid groups could be very protective about their members as attuning someone only for them to leave and join another group was a massive pain and waste of time and resources. And it happened.