Civ4 has a lot of SMAC aspects to it, basically player centric concepts that the AI can't handle or can't handle well, are sort of pointless or adds very little to the game, but fans cite as adding depth.
One such aspect is Relgion, as implemented, its a dilpmatic crutch and completely broken. The AI spreads it, has some rules it follow on how to handle it, but it never really understands it.
The other thing is the UN resolutions. False sense of power.