An interesting article in today's Guardian (UK) concerns a struggle for creative control over a movie. The author of the source novel(s) is willing to accept substantially less money to ensure that the movie does not ridiculously misrepresent her work.
"What for me is most important, and what disturbs especially the Americans, is that I don't talk about money. I could do a bidding war, but I don't want to, because the only thing that interests me is creative control, and they don't like that.
"When I got the first suggestions for who would play my two main characters in Inkheart I really got scared. The three movies will depend on the two male characters. It makes you really nervous if they suddenly suggest actors who are completely different from the ones you imagine. You know about the power of the screen: as soon as it's on the screen, children will imagine those people and not the ones you imagine."
Gee, what a unique concept: ask the author what would be faithful to the book. Almost without exception, the "bankable stars" rose to prominence on original scripts, not derivative properties. Does this mean that none of them are ever suitable for a derivative property? Of course not. But it does point something out that Hollywood does not seem to understand: that the draw for derivative properties is often the property, not the stars; and that the extra money spent on the most bankable stars would be better spent on other aspects of the production, or just plain in reducing the budget.
Then, many authors do not know the positive best way to make films of their books. They tend to be pretty good, though, at knowing how not to do the job.