Okay, so what do you think NOW?

[Sauron the White]

Meriadoc...
Perhaps if you watched the extra features, especially the commentary from the writers and producers, that comes with the special editions of the three films you would gain some explaination of why they did what they did.

It would take time - many hours of repeated viewings watching the same films over and over again but listening to the audio commentaries of different people who actually made the movie.

I do think that would provide you with an explaination and would help in understanding why some of these changes were made.

Besides that, there is the obvious difference between the art form of a book and that of a film. That would require a few book length postings to fully explain.