We have RPGs inspired by movies, but only one of the reverse, and it was recieved very poorly.
Well there was also Underworld, which was based on Vampire: The Masquerade, but they had to sue to get credit and compensation.
My vote would go to RPG players. They're the biggest reason why the industry and hobby hasn't flourished.
This is a part of it. I've been to GenCon and know that 99+% of the people in this hobby are perfectly normal folks. Its that fraction of a percent, the ones that have problems with hygene, personal space, and not acting like a child, that make people hesitate before gaming. Heck, *I* hesitate before gaming with new people sometimes! But that's not all of it.
Another big part IMO is the distribution model. RPG books are not books as far as retailers are concerned. With books, if you buy some and they don't sell, you return them. This is not possible with RPG books. They languish if they don't sell, sucking up space and making retailers hesitant to try new things.
I place some blame on the current model for traditional RPGs as well. They want to push books out to gamers. The way to sell lots of books is to market them to hardcore gamers, so we'll make games that appeal to hardcore gamers. Thus we get 4e (and 3e wasn't any better) with three books required for play and the assumption that each PC will buy at least one. New books rather than being aimed at GMs are aimed at players, to get them to get new powerups for their character, regardless of whether this makes the game more fun for the group as a whole. The other companies aren't much better, don't mistake this for a 'WotC sux' rant. The hardcore loves this, but the hardcore grows slowly if at all. And this makes games less accessable to new players, looking at mountains of books needed to play this game. The distributors are partly to blame here as well. The whole reason there's a PHB, DMG, and MM is because they wouldn't distribute a game line back then if it didn't have at least three books.
The hardcore also tends to make for long term games as well. Even if they aren't expected to buy books, dice, and spend time outside the game working on their character, the casual is expected to dedicate one night a week for the forseeable future. I think this is the biggest obstacle to getting new people interested. What if they don't like it? What if everyone expects them to come every time? What if there's a conflict?
The gaming companies need to get off the suppliment treadmill. The Indie games get around most of these problems. Many are written to be easy to start, have simple, direct rules, and are intended for short term play, if not one shots. Players play a favorite game for a couple of months, then decide to play something else. But the small-press nature of the beast means they are out of the distribution channel. Unless a store goes to a special effort, they won't realize that games like Dread, Mouse Guard, and Dogs in the Vineyard even exist.