I should be noted that one of the reasons New Urbansim became so popular was because developers are willing (and eager) to build these communities. While there are great things about walkable cities (nobody talks about walkable suburbs) from a developer's perspective they can sell smaller lots for the same amount of money as a larger lot under the banner of making things more "walkable". But it doesn't matter, because very few people that live in these communities walk anywhere at all. Since there aren't any big points of interest inside a suburban real estate development everybody just drive out anyway. Killer Cul-de-sacs is just clever marketing, nobody is out there tearing them up, they just build new developments and its much easier to get people to move in when they don't like their old street.