I don't think we can blame the war for Germany's and Japan's success afterword, nor defense spending. I'd attribute it more to the reconstruction of industry and government that they had to do after the war, and the US lack of corresponding restructuring. The short answer is that I believe they worked harder and smarter, and parts of our industry were a bit greedy.
If we had crippled the German and Japanese economies after the war, I think we'd be in far worse shape now. The screwed up treaty after WWI comes to mind. Without that, which I'd like to believe is the fault of the French, and of a spirit of revenge rather than sense, I don't think the Germans would have been capable of letting such a nut get into power in the first place.
That said, Pearl Harbor Day is a US memory, although there is certainly a huge bond between the US and British over that war. Lots of US sailors and merchantmen lost their lives bringing food and supplies to the British before we entered the war, and lots of British soldiers, sailors, airmen, and civilians lost their lives fighting the Germans before we were actively involved, too.