Have you read The Worthing Saga by Orson Scott Card? It's one of my favorite books of his and deals with a world in which a few humans with special power act as gods and watch over everyone, not allowing any pain. One day these "gods" decide that such a world has no stories, and they stop acting as gods, allowing the people to experience pain. (The book contains may of Orson Scott Card's earliest stories, I believe, certainly from before he started from Older Author Syndrome.)

This is why we can't solve the puzzle of how sex evolved by pointing directly to how it speeds up evolution.

I find the Red Queen hypothesis for how sexual reproduction could be useful after even a single generation very convincing.