If you are over the age of 30, it is likely you played on a merry-go-round at a park similar to the one pictured above. If you're under 30, it is likely you did not. They aren't around anymore, and I'm certain it's because kids got hurt on them, their parents sued park districts, and so they took them out. How do I know this? Well, this law firm's webpage not only talks about the requirements for any current merry-go-round, but also has a handy form to fill out if your "child was severely injured from playing on a merry go round." You "may be entitled to compensation for medical bills and pain and suffering." They'll get back to you within 24 hours.
Anyway, there's a camp we visited in Wisconsin last fall that still has them and so our kids got to play on one. Just look at the joy on their faces. Unbridled joy. There was nothing like running as fast as you could, then jumping on and spinning and spinning and spinning. If you know of a playground that hasn't yet had theirs removed, enjoy it. And tell me where it is, so my kids can play there.