High density low income housing used the be called 'the projects', and don't have a good track record of being pleasant places to live not least because of 'criminal class' inhabitants terrorizing the other residents.
I'm currently in London which I consider to be overbuilt, with the ancient underlying Victorian infrastructure struggling to cope with endless tower blocks of people, streets choked with traffic and tire pollution etc etc.
In the US there is plenty of land to build new towns and cities, why wreck the existing historical places with overbuilding when it would be more economical to build fresh, more sustainably built places for people to live...