I've read the hobbit but never the LOTR, but in the making of LOTR videos they point out (a few times I think) that Tolkein's writing style was highly unusual and extremely difficult to adapt to a screenplay. It's been awhile since I saw them but one comment they made was that Tolkein seemed to just keep the story elements flowing on and on almost like he was writing more of a historical account rather than a novel with a classic arc. What we got on film was the classic arc more or less, meaning they had to twist and bend the source material somehow. They basically thought that a faithful adaption would not have found wide audience appeal because Tolkien broke too many rules of writing novels.

I wonder though..