I don't know that I would characterize giving pieces of another country to the Germans as "neutrality".
That said, I am referring specifically to the "this Hitler guy probably isn't so bad" phenomenon that happened inside Germany and Austria. It was a dramatic failure to take a stand against Nazism, by middle class people whose neutrality on the persecution of untermenschen was motivated by a fear of losing their economic position (and the perceived economic opportunity of seizing the persecuted's assets. That is where the "socialism" in national socialism comes from, by the way), which overrode their ability to see all the violence and hatred that the Nazis wore on their sleeves. Its very similar to the neutrality of the Swiss during the same period of time.
I would guess for every moral WWII, there are 10 (if not 100) other wars that use the language of WWII and result in a complete waste of lives and money and cause far more problems than they solve.
If it wasn’t that way, Dresden and Tokyo would never have been firebombed. No one thought those missions were moral or good. they were in the service of annihilating the enemy for survival.
Arguably, the reason the Nazis came to power was that a great many right-leaning German voters looked at their options and thought "this Hitler guy seems pretty crazy, but that'll probably cook off, so long as he helps us beat the communists", which is a special kind of neutrality that people can never seem to shake free of.
I get what Kennedy was responding to, his sin was in failing to understand (just like the German right) that "leftist" != Stalinist/Maoist, and that a communist takeover need not look like the October Revolution, and the regime need not look like Russia ca. 1935, nor China ca. 1960.