Yeah, I've never understood the Roddenberry cult of personality, myself. I give him points for putting the thing together in the first place. I give him points for packaging it and selling it to the network.
I can't give him much credit for being an overly imaginative writer of SF-flavored television; 'Captain Kirk has a fistfight with God' wears thin fast, and 'crew visits planet which curiously resembles something out of Earth's history and can therefore be conveniently shot using sets, costumes, and props that just happened to be lying about the studio backlot' is a clever conceit from a TV production point of view but a little weak in SF/literary merit. I think the only one of GR's storytelling peccadillos that does not grow tiresome with me is his fascination with sex and beautiful women, because hey, I'm a guy.
And no, I can't give him a lot of credit as an admirable human being, for reasons already cited in the OP.
He was a TV producer, and one of middling quality at best; he was far better as a salesman. Seems to me that he got the message that no one was too interested in buying what he had to sell (literally and figuratively) after TOS; all he had to his credit was a string of pilots that never got off the ground. He caught lightning in a bottle with Trek, and the limit of his 'vision' seems to me to be that he recognized that people did like Star Trek, and since actually producing television programs was no longer a steady paycheck for him he could parlay being The Great Bird Of The Galaxy, The Visionary Creator Of Star Trek into a paying prospect. So he reinvented himself as the Great Humanist Dreamer.
The thing is, the vast majority of what I like about Star Trek happens to be stuff that other people dreamed up--Gene Coon, Dorothy Fontana, Theodore Sturgeon, et. al. If you want to know what pure 100% Roddenberry Trek looks like, watch "The Cage" (pretty good, but with clunky bits here and there), TMP (I like it, and a lot of other folks do, but it's far from universally beloved), and first season TNG (well, er, least said soonest mended). And I think part of that is because Roddenberry started buying into his own PR. There's kind of a steady downward slope you can plot by connecting those three points, and I suspect it's inversely proportional (if that's not mixing mathematical metaphors too egregiously) to how much he believed he was The Great Visionary. Star Trek went from being (intended as) a workable idea for an entertaining TV show, with a bit of substance at its core (Hornblower in Space/Wagon Train to the Stars, with the added wrinkle of using SF concepts to tell stories about socially relevant issues under the network radar) to being some kind of weird Gospel According To Gene about how wonderful and perfect (and therefore devoid of dramatic conflict or much useful storytelling potential) everyone will be in the future.
I guess I can't blame the man. Given the choice, I'd far rather be perceived by the public as this wonderful visionary prophet than as a womanizing, pill-popping boozehound of a TV producer, too.
But we all know that GR was only one of those two things, no matter how much he'd have preferred we believe otherwise (and how much some people still want to see him).
... Utopia. 
