The increase in appropriate density tends to make public transit solutions more viable [1] and you also (with good zoning practices) can make small businesses more viable too so you walk 5 minutes down the street for your local cafe instead of driving 15 minutes to Starbucks to send profits to Seattle instead.

[1] Car-only infrastructure isn’t viable economically but it’s hard to make that argument in this context because it’s the default and the costs are hidden.