> downside: - more traffic - more noise - more pollution - more anonymity, crime (people in small towns leave their doors unlocked and say hi on the sidewalk)

These aren't all foregone conclusions. For example, Arlington, VA (11th highest density county in the US) most likely has the lowest combined traffic/homicide fatality rate in the country. Traffic peaked in 2000, and by 2015 it had gone down 20% while population rose 20%. This of course required a lot of planning and investment, but that is enabled by the higher property tax revenues that more housing brings.

https://www.bloomberg.com/opinion/articles/2024-11-18/how-ar...