at least j.k. rowling has had an intimate involvement with the adaptation of her books into films. she even got to have input as to what director and actors would be in the movies.

i have heard she even gets say on final cut.

the tolkien estate had no control over the lord of the rings movies and i don't blame christopher tolkien for divorcing himself from those films which have almost nothing to do with the book it was based on.

As for Lucas while he remained in control of his baby and creation star wars he ruined it himself.

maybe having 100% control on a project and almost limitless funds is not a good thing.