Yeah, I'd much rather live in a walkable place with unpolluted air with a ton of ugly buildings, than a place with gorgeous buildings that needs ugly, polluting vehicles to get everywhere.
I agree I’d take your tradeoff if presented but I think the real world tradeoff is even sillier and more obvious than the one you propose.
I would argue there is no strong correlation here. A city can be walkable and ugly, lively and unwalkable, beautiful and unwalkable, beautiful but not lively...
This is mostly meant to contrast to non-walkable spaces, where to walk to a store in an American suburb often means walking in a 3 ft wide path next to 55mph traffic and the crosswalks for said road are a half mile apart, if you’re lucky. The safe paths are circuitous if they exist and the pedestrian signals, if you can get a green one, may take minutes to cycle to and give you thirty seconds to cross 6+ lanes.
Tokyo is an extremely organic city.
Typical Tokyo streetscape is heavy on modern blocky buildings, like this: https://sanpoo.jp/upload/yutenji-sanpo/yutenji_106.jpg
A school, playground, clinic, culture centre(which doubled as a movie theater and a regular theater), supermarket(s), pharmacy a dentist an indoor pool (still active, even though it's tiny) and several other things I won't bother mentioning because the list is already quite long.
But to me the most important part of that experience was that there was space between the buildings - green space at that - and the buildings themselves had mostly a total of four(including ground) floors, with a few higher units here and there.