I think there's the same amount of explanatory power if you just point at economic conditions. When the economy is bad, there is more crime, which tends to cent

I think there's the same amount of explanatory power if you just point at economic conditions. When the economy is bad, there is more crime, which tends to centralize in cities because the increased density means more anonymity plus a greater target market for thieves. Also, the 70s and 80s were peak times for young men who grew up with leaded gas poisoning. Previous generations did not have as much car pollution, car usage increased which led to those increases in crime. Perhaps quality of life is part of the equation but your comment tells us more about your preconceptions than about the reality of the situation.