"There is demand for a lot more housing in LA and other cities, which can only be met by building much more housing."
Why do you think you have to meet demand? (Also in a way that is against(!) the will of the people.)
Why do you even WANT more people in overcrowded cities? Is it some kind of Sim City worldview and you are trying to maximize population numbers simply because "big numbers are good"?
Imagine if your neighbor was like "yo, my family wants to live here, so I'll put a bed in your room, so my peeps can live there. And a bed in your kitchen. Also please empty a few fridge compartments, so they can use your fridge."
Anyway. I've addressed a few other points under your NYC comment.