I think the game would be far to time consuming if we had more cities. Remember you have to capture them all

Founding cities might not work well with the mtw campaign map either and the time period. A player who is dominating the game shouldnt be able to build metropolis' all over his empire, CA would need to make it very very time consuming and costly to avoid exploitation.

Founding cities and colonies would be nice if they ever do an age of exploration game