If you live in a truly walkable city you don't need a yard because there's parks. You also don't feel crammed because it's walkable and spend time walking around as opposed to a small yard or no yard where your options are to be inside or drive somewhere. And you don't need a larger house if there's a more appealing outside. Ayooooo these issues go away for most people when you introduce real walkable cities
Americans want their own private spaces and that preference is not going to change, especially when there is so much land available.
> you don't need a larger house if there's a more appealing outside
The outside is intolerable at best, if not outright dangerous for up to half of the year in much of the US. imo, our attitudes about walkability are due in large part to not having a mild climate like Europe.
It is always because they want a larger house, more land, and no shared walls.