I think there are two major factors to life quality that many American cities somehow missed or never really cared about enough, being able to stroll through cities by foot and decent work conditions (mostly reasonable work and commute times & holidays).
A friend of mine moved to L.A. in the early 2000s, he's still there, married to an American, but he burned out in his job there very quickly. No wonder, they were living in a small apartment with a baby in downtown L.A. and he had to commute for 3 hours daily. He got back at 10 to 11 PM and got up at 6 AM to get to work again - every workday, with almost no holiday. That's insane by European standards.
A friend of mine moved to L.A. in the early 2000s, he's still there, married to an American, but he burned out in his job there very quickly. No wonder, they were living in a small apartment with a baby in downtown L.A. and he had to commute for 3 hours daily. He got back at 10 to 11 PM and got up at 6 AM to get to work again - every workday, with almost no holiday. That's insane by European standards.