I can imagine the cities being useful for jobs and such. Players would be attracted to the cities if they didnt want to do something big, like an organization, for solo players it would be much easier to start a small buisness (AKA a bar/shop/restraunt) This is also good because it would propogate more economics. If possible i think it'd be cool for players to buy homes from other players, so people pay for the crazy detailed and complex building that they wouldn't be able to build, maybe due to lack of skill. I love the concept of a bustling city that isnt just there for looks. And the city having requirements would provide more contracts for people. I can imagine the worker in the electrical plant causing a city wide overload and then blackout.