Those merry go rounds were scary. I remember being on them and I thought it was hilarious to spin until you could hang off the side and fly in mid air. One thing I learned early was that the bike and I are not friends. I slammed my face like 20 times, and my tricycle one spun out of control down this hill in Korea.
I heard recently they banned rolling down the hill at our state park. I guess they don't want people to vomit.
As for risk takers, I think it's sort of true, but then again, a lot of stuff on the playground are not exactly safe. I'm pretty sure a lot of parents when they were younger played on some of the equipments on the playground only to be injured by it and then when they have children, they probably already know the risks so they tell them not to. I mean if I had children, I probably wouldn't let them play with a bike down a hill only because of my own personal experience with it.