Because the American people love the suburbs. That's all. The only reason.
The suburban layout is inefficient, dull, and soul-eroding. It's not an anti-American thing - suburbs in Europe are the same.
I have yet to meet someone who grew up in the suburbs who 'loves the suburbs'.
In fact, one of there few values of the suburbs is that they grow people who hate them so much they are inspired to create art, literature, video, and other projects on the subject.
The suburbs are like a Honda Accord, while city living is like a Ferrari. the ferrari evokes passion, but the honda is the practical choice. I'd love to move back to the city, but it is not practical for my family.
You haven't met me. I'm in my 50s and still live in the suburb and lovin' it. Cities are for visits.