Thats mainly because the arguments I have heard for making it less grimdark, is so that it offends less.By the way, your poll is extremely manipulative. The option you don't agree with is phrased so that picking it seems unreasonably prudish and conservative,
A decent parody should leave one asking moral questions, and questioning the morality of the parody. There is normally a line, but that line is the deference betwen depravity and immorality, imho. Even Chaplin managed to make light of Hitler, while exposing his ideals for what they were, or how about Dr Strangelove, life of brian?