Yeah, he had a hand in the making of the movies, but he should not be left by himself. Just look at how he's ruined The Spirit and turned it basically into Sin City.
I remember reading a story on Gabriel Macht, the actor playing The Spirit, buying a copy of The Best of the Spirit to study and Miller made him throw it out because he hated the book. If he hates the source material so much, why make a fucking movie on it?