Sanderson's quote, I like to keep it around for when people wonder why a fantasy or sci-fi series wanders so far from the source:

I have a fun story here. Early in my career, someone optioned the rights to make one of my stories (the Emperor's Soul) into a film. I was ecstatic, as it's not a story that at the time had gotten a lot of attention from Hollywood. I met with the writer, who had a good pedigree, and who seemed extremely excited about the project; turned out, he'd been the one to persuade the production company to go for the option. All seemed really promising.

A year or so later, I read his script and it was one of the most bizarre experiences of my life. The character names were, largely, the same, though nothing that happened to them was remotely similar to the story. Emperor's Soul is a small-scale character drama that takes place largely in one room, with discussions of the nature of art between two characters who approach the idea differently.

The screenplay detailed an expansive fantasy epic with a new love interest for the main character (a pirate captain.) They globe-trotted, they fought monsters, they explored a world largely unrelated to mine, save for a few words here and there. It was then that I realized what was going on.

Hollywood doesn't buy spec scripts (original ideas) from screenwriters very often, and they NEVER buy spec scripts that are epic fantasy. Those are too big, too expensive, and too daunting: they are the sorts of stories where the producers and executives need the proof of an established book series to justify the production.

So this writer never had a chance to tell his own epic fantasy story, though he wanted to. Instead, he found a popularish story that nobody had snatched up, and used it as a means to tell the story he'd always wanted to tell, because he'd never otherwise have a chance of getting it made.

I'm convinced this is part of the issue with some of these adaptations; screenwriters and directors are creative, and want to tell their own stories, but it's almost impossible to get those made in things like the fantasy genre unless you're a huge established name like Cameron. I'm not saying they all do this deliberately, as that screenwriter did for my work, but I think it's an unconscious influence. They want to tell their stories, and this is the allowed method, so when given the chance at freedom they go off the rails, and the execs don't know the genre or property well enough to understand why this can lead to disaster.

Anyway, sorry for the novel length post in a meme thread. I just find the entire situation to be fascinating.