I agree. In principle it should be an open system. If, in the course of the game, we may find out that some do better than others, we might start considering elections.
Micromanaging cities can become a tough, and still very important, job. Especially since you cannot give MM orders all the time with more cities is it very important to have a turnplayer who knows what he's doing. With one or two cities, we can easily discuss all little changes, but with 4+ cities that won't be possible as detailed as with 2 cities.