The main appeal but also the largest issue with the 4X genre is that it is based on a progressive utopian ideal, where every aspect of the society you control is always moving forward and improving. Every cultural change provides new bonuses over the last, each new technology researched only has upsides, every new population increases your production, etc. In the early game when you are building up all of the essentials this system works out very well, and it makes sense that these would have only upsides that allow for rapid expansion. After the early game this system usually falls apart, mainly because the exponential expansion has to significantly slow down when meeting other player's borders. Instead of expanding directly the player has to expand through other systems, which ends up with the player managing more and more systems for continuously shrinking payoffs. It doesn't help that all the other players also slow down at the same time, so there are no new diplomatic developments. Players usually get bored at this stage, and either spam end turn to try to quickly finish the game or start a new one.
I think that the 4X genre could greatly improve if there was some way to prevent this issue. If all of the players were not limited to only moving forward, then the game could keep the quickly changing nature present in the early game without resorting to complexity bloat. Diplomacy could drastically change as different player's empires would rise and fall. Decision making could become more interesting if cultural and technological changes had a mix of positive and negative impacts. Building up a great empire would be a more satisfying accomplishment if it wasn't just an inevitability, Figuring out how to manage a dying empire would bring new challenges to the player. The main issues are figuring out how to get the player to want to manage a declining empire, and in determining if or how the game would continue after a decline. Maybe an empire could be reformed after a decline, which the player would take control of, and a new period of growth could start with some influences from the previous empire's iteration. A player might have his empire rise and fall multiple times, but would need a reason to try to have each iteration succeed.
The main appeal but also the largest issue with the 4X genre is that it is based on a progressive utopian ideal, where every aspect of the society you control is always moving forward and improving. Every cultural change provides new bonuses over the last, each new technology researched only has upsides, every new population increases your production, etc. In the early game when you are building up all of the essentials this system works out very well, and it makes sense that these would have only upsides that allow for rapid expansion. After the early game this system usually falls apart, mainly because the exponential expansion has to significantly slow down when meeting other player's borders. Instead of expanding directly the player has to expand through other systems, which ends up with the player managing more and more systems for continuously shrinking payoffs. It doesn't help that all the other players also slow down at the same time, so there are no new diplomatic developments. Players usually get bored at this stage, and either spam end turn to try to quickly finish the game or start a new one.
I think that the 4X genre could greatly improve if there was some way to prevent this issue. If all of the players were not limited to only moving forward, then the game could keep the quickly changing nature present in the early game without resorting to complexity bloat. Diplomacy could drastically change as different player's empires would rise and fall. Decision making could become more interesting if cultural and technological changes had a mix of positive and negative impacts. Building up a great empire would be a more satisfying accomplishment if it wasn't just an inevitability, Figuring out how to manage a dying empire would bring new challenges to the player. The main issues are figuring out how to get the player to want to manage a declining empire, and in determining if or how the game would continue after a decline. Maybe an empire could be reformed after a decline, which the player would take control of, and a new period of growth could start with some influences from the previous empire's iteration. A player might have his empire rise and fall multiple times, but would need a reason to try to have each iteration succeed.