Cry havoc, and let slip the sacred cows of mockery
I'm somewhat agnostic on the "boobs" controversy itself, but I'm completely with you on the value of take-no-prisoners satire without sacred cows. I generally see MacFarlane himself as less than a pure practitioner of the art: like many others, he claims the mantle of irreverent humor, but he keeps plenty of sacred cows quietly and carefully protected in his pasture. Even when The Simpsons was at the height of its wit and relevance, it did the same thing.
I'd have to say the "South Park" team is closest to the anarchic comedy spirit of the big names you mentioned, particularly the Pythons. So many of these other "irreverent" satirists consciously exempt certain frequencies of the ideological spectrum from mockery... and that's without considering the very special case of the world's most special religion, where South Park found itself walking on ground where its network would not follow. If the discussion of sacred cows is expanded to include that gigantic specimen, the hypocrisy of the "edgy and irreverent" comedian becomes palpable, and utterly indigestible.
Tasteless mockery of people who thrive on being the center of attention is small potatoes by comparison. Although I find Ace's case that some of the targets were sincerely put off by what they were seeing to be persuasive, I'm not sure how sorry I can bring myself to feel for America's entertainment aristocracy, which is increasingly merging with our political ruling class. And I can't imagine any of them are going to seriously re-evaluate the system that is making them all filthy rich, at whatever cost to their dignity, until and unless paying butts stop dropping into those absurdly over-priced theater seats.