grimly64 wrote:As to why?
Because people familiar with the original story will probably watch the movie, since they liked the original (and they are going to be disappointed most of the times), people unfamiliar with the original aren't required to know it, so they can watch it (being probably satisfied because they didn't know how the plot was in the first place).
This usually maximizes the income...
Of course that's not always the case but most of the times it sadly is, and Hollywood didn't invent it (neither it is the most prominent user of this strategy).
I think that the "media" of a story is the most important factor in how it's structured and how it feels, a movie cannot obey to the same narration style and rules of a book, an animation work, a videogame, a comic, or any other work of art.
The opposite is also true.
I usually pass on movies adaptations of books or games because they are on a completely different level than the original, most of the times this cannot be avoided since the format is different.
For example, a big part of a book is that you actually picture the story in your mind, you build your own vision of characters and locations, you won't share the same vision of somebody else who read the book.
If you play a videogame, a big part of it is actually
experiencing the story while you play, it is "you" going through the story and
living it.
An animation work can be completely unrelated to reality, while still resulting plausible.