Exactly what Minneapolis is seeing right now with it's 2040 plan that requires upzoning basically everything to allow at least duplexes in interior neighborhoods, and more dense allow corridor routes, etc. The main arguments are "It will destroy the character of our neighborhoods", "It's just a boondoggle for developers", and "The current infrastructure can't handle the increased density". Really it's people who have their comfortable little neighborhoods and don't want those filthy renters coming in.