Let's pretend we live in a world where we all had a button. It could only be used once, and upon pressing it could never be used again. But upon activation you'd have the opportunity to go back in time, to rewrite personal history, even only if for a relatively brief moment.
Considering your life now, would you press it?
After some recent bereavements I've thought a lot about how I would like to, but obviously life doesn't work like that. On the other hand, perhaps our lives work best knowing that life is not a rehearsal, and we can live with regret and learn from it, but never rewrite them.