Matt Kahn and Ed Glaeser love NYC because they like its environmental footprint. But what are they maximizing? Not many new New Yorks are coming along these days. Newer forms are outcompeting the NYC form almost everywhere. This is no riddle.
Cities exist because they facilitate economic development. Market forces typically trump urban policies and we get the cities that work best. Even Manhattan's density keeps falling.
Few serious people will admit to loving Las Vegas or Houston or Phoenix. But their likes are the future. Even with European urban policies, the continent's cities are "sprawling."