That's basically the north-of-mainstream thinking in urban planning, right? I certainly agree with you, but I also think it is a wasted opportunity to just build what leading thinkers agree is a good idea.
E.g. this slice of suburban Tokyo: https://www.google.com/maps/@35.7368825,139.5634333,3a,75y,2... Note the speed limit is 30kph, or around 18mph.
This seems to be the default building style in much of Japan. You will still find larger streets which are arterial in nature, but they're usually still very bikeable and walkable, and still porous to smaller streets like the one linked above.