Why? Well, for starters, except for the Buffy, Angel and Star Wars series, which are based on the TV shows; most films are based on books, not the other way around.
I do think movies are a powerful tool to create interest. I watched Lord of the Rings Part I before reading the tome. Am currently reading The Horse Whisperer and have got Memoirs of a Geisha on standby; I have watched both of these movies. I read Bridges of Madison County because I heard it’s a good movie. Have yet to watch the film, though. Any idea where I can get a copy?
It’s much cheaper for the reader to create scenes in his head than to transform it into something that can be captured as visual images. Moviemakers need huge sums of money to make a credible film, and even then, many times, they flop. All said; it’s still interesting to find out how a director would transform those magical words into images. This is the main reason people watch Harry Potter- they want to SEE Harry flying on his Firebolt and put a face to Severus Snape. Therein lies the challenge.
Books have no time limit to adhere to. You can read 15 minutes before bedtime; read a chapter or a page and leave it for later if you’re too busy. You can take a break from reading if it gets too heavy. However, if a book is too heavy, it won’t be much fun to read, would it? The mark of a good book is one that transports you into its world and you can’t stop until its very end.
A moviegoer would not be willing to spend more than 3 hours max sitting in a cinema. Thus the moviemaker would be under pressure to keep his audience interested, make the movie understandable without losing the feel of the book. Many would compare both, just for the hell of it. I know I do.
But at the end of the day, I still think books capture best the heart and soul of its characters. They are able to explore the internal thoughts and feelings of the character and capture the reader in a way films are hard put to do. To watch a movie, you are already cast as a third party while books often put you in the place of the main character. I would treat movies as advertising, but books are the real thing. What say you? :D