"there was little sense of horror or revulsion at the prospect of all out nuclear war" I would wager that for most leaders it is simply a matter of not wanting

"there was little sense of horror or revulsion at the prospect of all out nuclear war" I would wager that for most leaders it is simply a matter of not wanting a "Pyrrhic victory" rather then an overwhelming sense of civility. Truman had no issues using nukes when there was no risks for doing so.