Well, one reason would be:

> long, shitty commutes

another is that some people prefer urban life.

I bet you'd be surprised to hear that in some countries people actually prefer to live in apartments to houses.When I ask why, they often state the fact that it is much less work to upkeep an apartment, so I guess that would be another reason. I personally understand why would some kid from the midwestern suburbs want to live in nyc, even if it means a much lower standard of living.

But in reality I think it really is purely cultural, people prefer what people like them around them prefer. People in the US were living in the cities as well before the "white flight", so at some point, urban middle class families were also the norm.