4) This is not new to Civ4, but: The AI often engages in pointless, long distance wars. Again, if you want AI conquest of other AI's to be a factor, it would be better for AI's to have a stronger inclination to make war on their neighbors.
Yeah thats another problem I have with the idiotic Firaxis AI. Not only do they huddle together on the same continent for millenia without even so much as spitting at each other, they will go way out of their way to declare war on you even when you are on the other side of the world. They cross oceans, sending a stack of ships carrying useless troops and make landfall (allways on the same spot, too). At best, they pillage your city squares while you take them down.
Yet, next to the invading AI in question, will reside a neighbor(s) whom he has been at peace with for 5000 years that happens to have fantastic resources which would greatly contribute to its economic development. Much easier to conquer. Much easier to deal with city maintenance upon conquest. The benefits of reaping the rewards upon such a conquest are abundantly clear: Expansion. Something they cannot do if they wage war with a civ (usually human) on the other end of the world. "Naah... we wanna attack the human player instead! He refused to stop trading with our enemy, or give in to one of our ridiculous demands! Our neighbor shares the same faith, we could never attack our close friend!" Pathetic.
This whole issue has made the game dumb, and outright unrealistic. Greed takes precedance over religion in the real world when it comes to politics. I have grown so bored with the lack of inter AI action, coupled with the insane anti human bias in my games, that I have since uninstalled it. Civ4 is a great game, but the AI messed it up completely.
Firaxis, focus your attention on making the AI less human biased, reduce the diplomatic bonuses that same religions give, and for Pete's sake step up the aggression levels between AI's, esp when they are neighbors. More inter AI wars make the game interesting! Once again, refer to Civ3 to see where we are coming from.