Ray MacL. Has It Right
Carl K.

I agree with Ray. Tolkien's passion was language and its role in the development of culture and its history. As an avocation, JRRT created first the language of Elvish -- it derives from Finnish, the Nordic orgins of English language an literature being his specialty -- and thence invented for his pleasure the cosmology of Middle Earth and a mythology to go with it. Thus the Silmarillion -- creation myth, pantheon of deities, the rise and fall of worlds and peoples.

Early in the LOTR we read him saying that "the tale grew in the telling", and like many great story tellers, he walked out of Bilbo's front door and followed the path where it took him.

This is why there is a Bombadil. One might imagine Bombadil as Tulkas; the main story doesn't need him but JRRT wanted to meet him anyway. Had he written back to front, Bombadil might have ended up on the cutting room floor.