Making a decision tree that fits "everything I want this AI to do" without neglecting absolutely anything is difficult. Unrealistically difficult. It's more a question of how much neglect is acceptable. You're not wrong (civ 5 was terrible on release in so many ways, only some of which got fixed). One doesn't have to aim very high to go further when the barrel is on the foot. Most of the civ 6 complaints do indeed have obvious civ 5 parallels or are even direct ports of civ 5 problems (unit cycle force selection is a carry-over! Same with UI lying about when you'll attack for example). The perplexing thing here is the civ 5/6 split. Their release quality is pretty similar, and they share a ton of issues. In contrast to civ 5 and 6, which share a comically bad UI, they need to put a UI programmer on the game and leave him or her on the project until after alpha ends or that's not going to work. MP is even more dependent on controls and pacing than SP, and Firaxis has chain-regressed at it for the better part of a decade now. Transitioning THAT to MP? Good luck.