Tolkien did more than just write the Hobbit and Lord of the Rings. He was a professor who emphasized the study of the epic. In fact it is due to a lecture he gave in I believe 1936 that brought Beowulf to the forefront of literary studies, which has had a lasting impact.
He is also responsible for creating an entire fictional language (elvish) that is loosely based on Gaelic and Welsh, which he started working on when he was a child. The world building was only actually done to have a place for elvish to exist.
That said, I do find LOTR a very difficult read due to the archaic forms he used, and I don't think its Noble Prize material, even if it did start the fantasy genre. Several of the characters are rather flat, with only Bilbo, Frodo, and Aragorn really being round characters.