Anyone who has lived in a rural area that hasn't been subsidized can tell you why spreading out kinda sucks. The power company charges you $100k to run a line to your house. The phone company charges you $20k to run a copper line to give you 100kb DSL. Water has to be pumped from a well which costs $30-50k to drill.

We don't really need to cram people in elbow to elbow like New York City though. We just need walkable downtowns where you can pop on down the street from your apartments to the market to get ingredients for dinner. Even just building our houses closer together and putting in dedicated pedestrian paths is enough honestly.