Because attempting to reach a political settlement to stave off military action is unheard of? It was unsuccessful but nevetheless had to be attempted.
Appeasement goes way, way back, so it isn't unheard of at all! The real issue is whether it "had to be attempted" with Nazi Germany. Standing by while Germany repeatedly violated the Versailles Treaty was unwise, not only in retrospect but as argued by many influential people at the time. You (well, not YOU, of course) got the result they predicted. Why would you expect the US, which wasn't a party to the Versailles Treaty and therefore had no standing to enforce violations, to immediately jump into the war the Euros had gotten themselves into? (I know, I know, because that's what we do.)
What I said was that the US was instrumental in winning the war, but it came as no surprise to anyone when Germany invaded Europe, and had the US got involved before the fall of France it's reasonable to surmise that the Germans would have been repulsed, in fact had the French not run away and actually fought alongside the British as they said they would do, there is a fair chance that France would have held anyway, and US intervention at this point may well have prevented Pearl Harbour.
Once Japan's access to steel and oil was cut off by the 1941 US embargoes, there was no face-saving way for the Japanese to avoid war, whether Germany was in it or not. That was a war we brought on ourselves - sort of the reverse of the ETO.
- oldman
