content: Because Hitler hated ugly art (e.g. he displayed examples of the art he didn't like in the "Degenerate Art Show"). And when he lost the war and the communists and the Jews told those stories of "gas chambers" and "electrified floors" and the Nazi officers were all subsequently tried at Nuremburg, society became ashamed of such monstrosity and developed a reaction formation to all things Nazi. So from this new perspective formed in reaction to Nazism, if Hitler hated ugly art, then ugly art must be the epitome of taste and artistic excellence. This cultural reaction formation to Nazism and its subsequent cult of ugliness  is called "postmodernism" .