Presumably, a book (or comic, or toy, or whatever) is optioned to be a movie because people liked it. Bearing in mind that films must differ from books because of the nature of the two media, why mess with what made the original work?
In other words, why buy the rights to make a film based on a book, then make a film that only shares the name and some minor details?
I thought LOTR, Narnia, and Harry Potter were finally turning the trend back away from this stupidity. But I just saw an ad for Bridge to Terabithia, and I don't think I've seen anything that looks to be straying further from the source material.
Well, except for another upcoming movie that's received more hype. I won't name any names, but Peter Cullen will be playing the major role.
I just don't get it.
And it's not like all movies in the past have been radically different, either. To Kill a Mockingbird is almost 50 years old, faithful to the smallest details, and a damned fine movie for it.