This is related with the housing discussions. People have somewhat convinced themselves that cheap standalone houses are the goal. Which, I suppose there is no reason that can't be the goal. But compare average home size in pretty much any US city with some of these walkable cities you have in mind.
When I do that, I start asking how related those two things are. And I'm growing rather convinced that people have built up a mental idea that they can live with all of the benefits of both worlds, without contending with the contrast between them.