Those cities are overpopulated. All areas that involve multi story buildings are overpopulated. Too much population density is ALWAYS a problem, is always preventable, and is always the fault of those who don't have the sense to keep it in their pants, don't have good birth control, or don't understand the realities of there being finite resources on planet earth, and instead of using logic to make their decisions, they follow their emotions, which is damn foolish. It is always stupid to follow emotions at the expense of logic.
Ideas, emotions, and love can all be infinite without any restriction whatsoever, but physical reality is NOT infinite, and the planet's resources aren't unlimited either. People so often make emotionally based decisions and then wrongly expect physical reality to accommodate them. there may have been room for human expansion 600 years ago without thought of restraint, but that was a long time ago, and I think that human beings are still stuck in the expansionist mindset without worry since the beginning of humanity for hundreds of thousands of years or more and somehow are just so habituated to that kind of attitude, much like animal instinct, that they have a difficult time accepting the reality of living in a way that observes that there is no more room.