I agree that "weapons of mass destruction" should never have been invented, nuclear weapons in particular.
Nuclear weapons absolutely had to be invented when they were, by the nations that developed them, because ultimately, they served as a deterrent to broader conflicts and saved lives. Had the US invaded Japan during WWII, tens of thousands of lives on both sides would have been lost, the war would have been prolonged, and the later Cold War could have easily escalated into another World War, albeit a conventional one, between the US and USSR. It may be strange to think of it, but nuclear weapons have brought some measure of peace during our lifetimes, when for hundreds of years of conventional war, there was not.
Marvelous! The super-user's going to boot me! What a finely tuned response to the situation!