Most ride deaths are caused from error on the rider's (or guardian's) part or something unknown to the person of a physical condition undiagnosed(from what I've studied up on, anyway).
Getting rid of thrill rides isn't going to solve the problem. It's getting rid of ignorance.
The very first Disneyland death was on the Matterhorn, a thrill ride. Yet the 15 year old that died lost his life before anything extreme was happening with his bobsled. He had gone with a group of friends and was currently in a fight with his girlfriend. In a fit of testosterone, he stands up while his bobsled is going up the first huge/steep lift hill. He loses his balance, falls out, and gets crushed at the bottom. Had this boy listened to clear instructions to remain seated at all times, that would not have happened. It's sad that a boy at such a young age died, but obviously he didn't listen to safety instructions.