Yeah that is far more logical - The pics in your other post illustrate the concept well. The major hurdles are transportation and retrofitting. New towns and construction are well and good but for adoption to take off benefits must outweigh existing convenience and not eliminate mobility overall. Scalability is another one.
It's a lot to try to balance. Designs I've seen get the most traction involve reclaiming blocks and offering elevated rail to move about or use of subway where logical. The more modular the better. And I've seen a few like that get /close/ but they'd strike out on scope or would piss in some lobby's cereal and get early enemies. That one's a minefield.
I feel like we could see some rapid creep if someone got the ball rolling and it was reasonably successful... but that's a hell of a big step to take. And make no mistake - it will be a retrofit that starts the creep. Has to be a city or a substantial dense town to draw interest.