@ddljohn-- I don't think trampolines are dangerous if there is protective equipment. Of course, I don't think young kids should be allowed on it and parental supervision is necessary.
My kids are ten, twelve and thirteen. We got a backyard trampoline last summer, but we also purchased safety nets. They also have protective gear that they have to wear before they go on it. I might go in the house for a few minutes, but I'm always keeping an eye on the kids while they're on the trampoline otherwise. So far, we have not had any injuries.
I don't regret getting a backyard trampoline because it's a lot of fun. I also jump on it sometimes. It has given the kids something to do during the summer months.