Actually, I think the movies could have been done differently. While Gollum was the great "creation" of the movies, I thought that whole huge sections of meaning were lost in the films translation from the books. It was a strongly Catholic work and much of that got left out.
Yet, wouldn't Tolkien disagree with your assessment of it being a "strong Catholic work." He wrote over and over that it was not an analogy for Christianity or World War II or even nature versus machinery.