The capital for renovation is not being put in the hands of the residents. That and the institution of private property are the main problem.
Like intentional efforts to bring low income people live in wealthier areas, this could have positive effects. Pricing people out of their homes, and communities is awful.
Some areas the social services are too overwhelmed to help people. It still isn't right to herd people in New Orleans onto a plane, and give them zero information, until they read, 'Welcome to Omaha'.