Surely whatever dangers kids are exposed to in cities absolutely pale in comparison to the increased risk of car accidents caused by living in the suburbs, where virtually every outing requires a lengthy trip by car.
Look around "kid-friendly" suburbia, and there's practically no kids outside.
Then again, suburban dwellers aren't totally crazy because our large cities are also built for cars with space for people as a complete afterthought most of the streets in Minneapolis need a road-diet. In Minneapolis, we invented the mall (Southdale), which sucked all the retail life out the city then we added the 'Mall of America' just to finish the job, to add insult to injury we built preposterous skyways which divides what's left of our paltry street-life onto two levels.
I really should move to Europe: Paris, Milan, Utrecht, Munich, London, Budapest, Prague... heartbreaking beauty.
What people are referring to on this thread is really exurbs.
The one catch is the risk of my kid being squished like a bug by idiot suburban drivers.
And kids, in my experience, hate suburbia, especially as they get into early teens and want some independence. It's like living in a giant protective bubble where there's nowhere to go and nothing to do, without having to have someone's parents cart you around.