where "good" is defined by demographics

Whoa. The "demographics" people are choosing on are income, not race. Faced with a choice between living in a middle class majority-black neighborhood and a (forgive the term) white trash neighborhood, I think most people would choose the former. This fact may get obscured by the relative paucity of middle class majority-black neighborhoods, but at least in the US, that has at least as much to do with redlining, the legacy of sundown towns, and such as it does with HBD.