The public realm in America has two roles: it is the dwelling place of our civilization and our civic life, and it is the physical manifestation of the common good. When you degrade the public realm, you will automatically degrade the quality of your civic life and the character of all the enactments of your public life and communal life that take place there.
Edit: There was some talk here a while ago about roads that were built by developers "for free" and then given to cities for maintenance. Sounds good on paper but results in ridiculous amounts of roads being built... Anyone remember a good link for that?