Still no truly meaningful Diplomacy, though. Why can't Civ games ever have real diplomacy??
Come now, they have
very detailed simulations for dictators suffering breakdowns and ranting about the final and imminent destruction of the infidel.
More seriously, I'd like it if they could build some sort of mostly separate subsystem for diplomatic relations, so you could get into more detailed and irrelevant things than just trading copper or getting miffed at catching a spy. One of the things I loved about Alpha Centauri was that other factions would get pissed at you for running your empire wrong. No effect on them whatsoever, it just morally enrages them that you're inflicting Democracy and Free Markets on your own people. Something like that could be applied a bit more subtly, like regarding poaching or drugs or even just art or censorship, which might make things interesting without screwing with the main game too much, I think.
I can see it now. The Egyptian Prime Minister could call you up to tell you that gold is the work of the devil so you need to stop using it, and you could reply by mentioning that his country's public nudity laws have just
got to change. The Russian Consul could contact you a bit later, confiding that Greece's illegal persecution of quack doctors has reached a boiling point and requires immediate military intervention, and that if you help out they might be willing to work in that ban you've been looking for on ever impugning the noble and virtuous duck into its new constitution.
I did
not realize I wanted that this badly.