I assure you that the Americans of the WW2 generation did not think that way. That, too, was a sloppy war, often poorly planned and executed, particularly the first two years. Japan attacked us, but Germany did not. Really, it took Pearl Harbor to wake up the U.S. to the fact that imperialists in Germany and Japan were busy imposing their way of life (and gummint) on others, except in their case it was fascism.
Up until 1941, America had shown little interest in meddling in world affairs. The point is, the whole American philosophy is a commitment to freedom, that it is worth fighting and dying for. Does this mean war every time? No. Sometimes, however, it is necessary. And I guarantee you that Western Europe is happy that (how many?) American boys died so that they could have "our" standard of living now, rather than the alternative. (Its present situation -- marked by a rising Islamic population and an unsustainable welfare state -- is a different matter.)
What is debatable, of course, is whether Iraq II fit the bill. Was war the last option? I'm agnostic on the matter. Saddam had been misbehaving for many years. But America's specialty is freedom, and we should aim to export that as much as possible.