The 'Charlie' remake looks to be another example of trying to get closer to the author's vision, like when they did that TV miniseries version of 'The Shining'.
In regards to the Batman movie, I think they did about as accurate a Batman that they could and still cash in at the box office. The Detective Comics Batman is even darker and more violent than the Tim Burton movies, but then how do you sell that to younger audiences? I think it was a compromise with Burton and Bob Kane, who gave his seal of approval of it and even had a minor part in the first Batman movie. Kane got to see a darker version of Batman, unlike the 60's TV show that many remember and love (myself included, I admit) and Warner Bros. got a movie they could still sell to younger audiences, allowing for the merchandising cash cow to rake in the dough for everyone. I'll bet Jack Nicholson, who had that ridiculous percentage deal in lieu of a salary, was quite happy at how it turned out.