It's an interesting question. Before and during WWII, it was very popular to mock Hitler, because of the general over-the-top pompousness of his oratorical style and public image. (http://en.wikipedia.org/wiki/The_Great_Dictator, http://en.wikipedia.org/wiki/Der_Fuehrers_Face) Afterwards, the general attitude was one of somber, shocked horror. I'm not overly bothered by the fact that people have gone back to laughing at Hitler. I don't think people have forgotten the gravity of his crimes so much as they've become willing to use that as a backdrop for juxtaposition.
