Movie Versions of Books

It seems like every movie put out these days is unoriginal and taken from a book. I’ll admit to watching movies without reading the book first. But in that case, I feel like if I read the book first, I’m going to be disappointed when I see the movie.
In such an instance, one of my friends commented on the recent hit, Twilight. She read the book first and then saw the movie. She said she pictured the main girl, Bella to be more awkward in the movie as she was in the book.
One of the things with reading is you get to imagine what happens rather than someone describing a scene in one certain way.
With reading a book, the author gives such detail that allows a reader to be creative and come up with their own little world inside their head.Another thing with creating images, when seeing a movie after reading the book, the viewer can sometimes get lost in the movie version and forget what they had imagined from the book.
I know when I read some of the Harry Potter books, I had certain images that developed in my mind from the book, but after I saw the movies, it sort of distorted my mental images.
Also, some books are over 500 pages long. If movies adapted the plot page by page, it would be well over 3 hours long. Why else is the third Lord of the Rings movie was about 3 hours long? It was because they had to condense almost 500 pages into a reasonable length for a movie. But with that, you lose vital information to a story you normally wouldn’t know if you watched the movie version.
And even when movies use most the book, they add their own spin to it and put scenes in a movie that weren’t even in the book.
Take for instance The Count of Monte Cristo. I have never gotten around to finishing the actual book, but I know enough about the differences between the movie and the book. The movie completely destroys the book from the way people die to Dantes having a son by Mercedes, which he never did in the book.
Although I have seen movies where I have not read the book, I know well enough that 99% of the time, the story written is better than the story perceived on film.