Unless half or more of planet explodes, it's always a terrible idea to go back in time and change history. Especially when the event you're changing led to extreme lessons for first-world governments to learn from, massive leaps in technology, and the overall progress of man.
It's especially nonsensical when you think stopping Hitler is the world's worst event that must be altered and not things like killing Baby Ghengis Khan. Choosing which evil figure to kill is arbitrary. Better to allow history to happen and learn from it than try to change it unpredictably.
But again, if half the planet blows up due to simultaneous nuking, then yeah, you should probably prevent that.