[Finwe]

Eomer, it wasn't an improvement. It was merely a change to the books that enabled the audiences to realize how the Ring was affecting Frodo. In the Books, we could read about his emotions and mental reactions, because we read it from an omniscient narrator's point of view. It is only later that we find out that it is Frodo who wrote it, thus, enabling us to "see" further into his mind. In the Movies, however, we don't have anything to read, ergo, we can't see directly into the characters' minds. That was why the Frodo-Sam relationship was changed. We can't read their minds when they're on-screen, so the subtleties of their relationship became much more obvious.