I think some of that "hate" is just hype, bought and paid-for, for the Media. Really, people didn't like Upton Sinclair back when he was alive either--they didn't like his articles and really didn't like his fiction.
But he earned himself an honest living and in time, the meat-packing industry he reported on in "The Jungle" did actually improve somewhat. He got results.
Michael Moore is much the same way: he's earning an honest living, much to the dismay of your Fox News Heads. It's a pity he's not getting results yet, but hey.
Too Long? Let's just say: the United States is run by a _tiny_ clique of very stubborn and elitist rich people, who are hellbent on doing things their way, and mere citizens like us be damned. To challenge that, like ever, you have to be relentless, you have to be a buzzkill and you have to be obnoxious about it. It's not enough to tell the truth--you have to beat these nimrods over the head with it until they submit. This doesn't make you a popular person, you know?