I think I understand this perception to be the product of youngish, upwardly-mobile, well-educated people who are able to build enormous, fluid, flexible social

I think I understand this perception to be the product of youngish, upwardly-mobile, well-educated people who are able to build enormous, fluid, flexible social/friendship/dating networks throughout their 20s living in L.A. or NYC that they couldn't build in St. Louis or Kansas City. They're actually mostly right about that. [0] The problem is that the perception remains well beyond its usefulness. Mid-sized Midwestern and Southern cities have everything a married couple in their 30s with (or without) a couple kids could possibly want -- all the stuff you mention and a lot more, really. And they provide it with a COL-tradeoff that can't be ignored. I have a fairly good idea what people in New York think of my hometown and other cities like it and, frankly, they're wrong far beyond otherwise reasonable differences of opinion (as in they hold what are inarguably factually incorrect views (about, say, the size of Midwestern economies, the availability of jobs, the number of cultural institutions, the experiences of people of color and homosexuals (in urban centers, admittedly), the prevalence of ethnic restaurants, and on and on). [0] I think it's exaggerated (especially in the sense that it's not for everybody), but real.