There isn't an option here for "no leader traits", alas. Though I'd also like fewer, i.e. no, unique units and buildings, no unit promotions, and no civics.
That already exists; it's called Civ II.
*snort* Do you really want my analysis of everything that is wrong with Civ II ?
Remove the annoying and lagging 3D!
Unit promotions: personally, I find this extremely tedious, so I usually play with the option for units to auto-promote *gasp*. A unit with several promotions carefully chosen will not stand a chance if you don't have a technological edge over other civs. Then you will lose it, and then another one, and you feel it was a complete waste of time to chose promotions for them.
Tedious, yes but a level 7+ horsemen that is carefully upgraded to a gunship has the overwhelming odds against a tank.
Actually, can we have less war in the game, generally? Or at least make it much harder to declare it (Alt+click on the leader, come on!) or, rather, to come to a situation where it can be declared? I know war is historically very significant, but in my opinion it is far too whimsical in the game.