I don't really agree with that. I have family in both Nashville and Raleigh. By both their estimations and mine, both cities have gotten quite a bit better over the last ~20 years.
I'd also say NYC--for all the complaints about Disneyfication. As a visitor, I'd much rather have today's 42nd Street, Lower East Side, Chelsea, etc. than I would the 1980s version. People have certainly been priced out but, then, it's not like Manhattan was cheap even in the 80s.
Next reason would probably be general cleanliness and drastic increase in homeless.