While I understand why they removed it, I still kind of miss the ability to buy cities wholesale (finance revolts) in Civ 2 if your economy was strong enough. It was a simple way to expand your influence without causing a major incident (unless you wanted to).
Yeah, that was always fun. One thing I never liked about the diplomacy AI in any version is that real horse-trading would never happen unless one side completely outclassed the other--which would result in the superior side demanding
cities and tribute.
In the real world, a bloody war with good odds on stalemate would result in significant trades on both sides: territory, goods, money, etc. In Civ IV I could occasionally get civilizations to trade cities to me, but again--only when I totally outclassed them and the city was indefensible to begin with.