It's a great movie that's often misunderstood.

The writer wanted the audience to laugh with Hitler, to cheer him on, to emphasis with him, to see him as this likable, but ultimately harmless person. "Oh, his suggested causes of and solutions to problems are obviously ridiculous -- but what do you expect? He's a comedian ... but he kind of has a point about real issues we're facing."

People have forgotten that's how Hitler was seen during his rise to power, and just like in the movie it's only after it's far too late that people realized what kind of person they're enabling. The ending monologue even has Hitler straight out saying he's happy to "play the clown" as a means to his ends.