Even ignoring the "its just" cosmetic argument, until shortly after the Horse Armor precedent was set games were usually filled with cosmetics. They still existed without needing 2.99$ to motivate the creators, and often added a huge amount to the game in terms of things to do. Fuck the entire original God of War game built its entire replayability on unlocking costumes.

Heck even the Ubisoft "time savers" MTX used to just be fucking cheat codes or straight upgrades built into the game.