One other point I wanted to address. One negative side of sprawl is how it affects natural environments - but, again, does it really have to, or do we do it just because it's the easiest and cheapest way to implement it? It feels like living less densely could actually be beneficial for the environment if done right, compared to the cities. Consider: a metropolis will always carve a chunk out of nature and replace it with a dense grid of roads around high rises, completely ruining the ecological system in the affected area - heck, our cities even have their own microclimates now, because of how much heat we pump out at once in a single place.
On the other hand, a single residence does not have a significant impact; and if you space them out sufficiently, you can preserve the original environment in that space between. Infrastructure is trickier and more invasive, but we've seen some trends towards more localization recently (e.g. with residential solar, composting etc).
Who knows, perhaps we can actually make this description from "The Diamond Age" a reality?
"The prevailing architecture here, among those who had not adopted neo-Victorian precepts, was distinctly subterranean; as if these people were somehow ashamed of their own humanity and could not bear to fell even a handful of the immense Douglas firs that marched monotonously up the tumbling slopes toward the frozen, sodden ridge of the Cascades. Even when it was half buried, a house wasn't even a proper house; it was an association of modules, scattered about here and there and connected by breezeways or tunnels."
