Even setting aside the racial component for a second, it stands to reason that if cities are "tough" because everyone with the means toward a more stable and comfortable life moved to the suburbs, then many of those same issues with poverty and resulting crime and drug abuse would be lessened by un-segregating things.
If cities are rough because it's accepted that anyone with the means will leave, then they become less so when the urban/suburban split doesn't mirror the poor/rich (or white/minority) split.
Suburbia offered nothing in this regard. It was a contentless, vapid expanse of nothingness, where I couldn't go anywhere or do anything without being deliberately driven there by my parents.
Large cities are no place to rise children they are cramped, expensive and highly polluted the kids may get exposed to a higher diversity of people but that is not necessary at a young age. As long as you raise your children with your own values and teach them to have and open and accepting mind it doesn't matter where they are.
I have no problem interacting with different kinds of people even though i only got exposed to such diversity after i graduated university and I could never imagine growing up in a large city it would have been awful.
Hell personally I'm trying to move to a smaller city close by to London and take up more remote work so i can actually have more breathing room.
I absolutely have the expensive, small and badly maintained spaces that tend to be the norm in large cities.
US cities are a bit different you could probably live comfortably if you are ok with needing to drive everywhere but that's ridiculous to. I don't have a driver's license I never needed one since everything I ever wanted was a walk away and if it was further I could just take public transportation even in the small city I grew up in.
Spending so much money maintaining and fuelling a car is a waste of resources.
And I'm not sure even those would be "highly polluted" these days (big Asian cities definitely are though - and I wouldn't want to raise my kids in New Delhi or Beijing).
My wife grew up in Vienna and my son will grow up in Berlin, I think both provide for a much more interesting childhood than the suburb I grew up in, and are not really polluted or dangerous (maybe some parts are, but we don't have to live downtown to get the benefits of the city).
Berlin in particular has a lot of late 1800s "railway suburbs" which have been politically integrated into the city-proper in the 20th century & are now just outer districts of the city.
These are plenty green and still well served by the city's rail and subway network, so you sort of get the best of both worlds (commute times are still longer compared to living in a more central district, but that highly depends on where in the city you work).
I will never complain about pollution again (I'm not saying any amount is good, but there are children all over the world living in much worse conditions than London at 17:30).
In suburban environments (I don't have a direct source right now, but it's sorta of widely accepted) kids often are among peers exactly like themselves. This really does nothing for development, especially if 90% of the school is of a certain race/culture...which typically happens in divided suburban environments.
In addition to this, they are also exposed to the realities of life. Seeing homeless panhandling, the speed of the city, the ever changing environment, it's a good representation of what someone might face in life. Being exposed to these elements builds a stronger person.
Sure they might have an overall different outcome of life, for example kids certainly aren't dirtbiking/atving in the city, but that all comes down to exposure, parenting, and self interest.