Director's cuts

Listening to the commentary for the Director's Cut of Donnie Darko today, I came to the conclusion that the director's cuts of movies are roughly analogous to the pheonomenon of band members switching instruments just for fun. You know: the bassist plays guitar, the guitarist plays drums, etc. It's cute if you're a fan, but that's about it. Directors should direct (with some exceptions). Let the editors do their fricking job. Extended editions that more involve the whole team are a different story.