Well, you see, in the movie business, there's this job called "editor." And such a person takes what the director and all the others shot, very often without having anything to do with the process up to that point and cuts it into a coherent film, because that is their art. And, while of course the situation with fan editors is a bit different, I still don't see any harm with someone making their preferred cut of a movie, since they're only editing a copy of the film and it has no bearing whatsoever on the version preferred by the original creator. It's like if I bought a printed replica of a famous painting, I don't see why I couldn't make a photocopy of it and paint a few extra things on that copy before hanging it on my wall. And if my friend happens to like it, why not make a copy for him? In fact, many artists have done similar things, taking a photo or a copy of a famous piece of art and changing it, so that it became a new, different piece of art.