Were there any "Hitler Cantatas"? I have always wondered about that. Why are Stalin and Lenin "OK" but not Hitler? I guess because Stalin "won". Stalin murdered way more people than Hitler.
I sometimes wonder about that too. There were officially tolerated composers in Nazi Germany whose job it was to write propagandistic music for the regime, same as in any country, but they're all completely forgotten nowadays and even the slightest hint that a composer was affiliated with the Nazis puts a serious damper on performances of their music (well, apart from Orff, perhaps). Yet not only has the music glorifying Stalin survived but it's also notably more popular than most of the music that was officially banned or censured. (Look at the Shostakovich symphonies—2, 3 and 4 considered too "formalist", and nowadays rarely played outside complete cycles—5 and 7 and 10 showered with official honours, still heard all the time—13 and 14 as close as they come to actual critiques of the regime, how often do you hear those?) It makes you wonder if Zhdanov was on to something.
Of course, Hitler's regime only lasted ~12 years, and he had a bad habit of sending anyone who looked too intellectual to a death camp, so the amount of Nazi music out there is significantly smaller.