The only halfway good argument against 15 minute cities is that kids aren't safe on their own. Which is true in terms of how cities are currently set up where kids might have to cross a six lane highway to get to school. Or they might be forced to walk across someone's yard and the house could belong to a deranged racist with a gun just waiting to start trouble with whoever walks by.

But these types of problems are remedied by having more dense urban areas to begin with. I've been to Japan and China and one of the most striking differences over there are how you'll see kids walking around unaccompanied by adults. Kids exercising more independence and autonomy at a younger age is a good thing. Not to sound too boomer, but I think it instills a sense of community and responsibility into kids if they're not always reliant on their parents driving them everywhere until the age of 16.