There is a lot of really good stuff from civ1 and 2 that's missing.
captured city- In civ 1 this made the empire break up in two warring factions, one allied to you, another hostile. Makes perfect sence!
Controle zones-One of the benefits of controle zones was that other civs couldn't just walze into your empire, if you positioned border patrols the right way. I HATE having some other civ walking around deep inside your territory, even allies.
I would also like the following modifications, buts thats later, gotta go now.