It was a long time ago, but I did read the Hobbit. In terms of film-time, you are right, but in terms of reveals and importance, it's pretty much the only thing that connects the overall arch, that I recall.
But it is the end game of the story. It's the "thing" that is suppose to grab you. It's the mystery, the allure and it's already been not only already been revealed but concluded. The hobbit isn't much of an origin story for anyone but the ring. The rest just reveals how cyclical the hobbit is to LOTR minus the urgency.
This movie is completely unnecessary to me. I guess I don't mind prequels, but prequels that don't really reveal much about the sequels I guess I do mind. Even the Golem's origin story has been explained, if I'm recalling the movies properly. If you just watched the movies, you may not know the EXACT story of Bilbo Baggins, but you don't really need to. You get it, in one short scene, you get it.
I actually thought it was brilliant to go straight to the LOTR and skipping the hobbit. That way, the golem, the ring and the hobbits are "discoveries" to the movie-goer. The reveals are plenty. But those reveals are over. They put the meat on one plate, rather than dividing it up and diluting it. You can't go back to the slower preequel after making that decision. I'm not saying this is the next Matrix 2 or anything, but it has more in common than I can support.
Some things that are 50% explained/assumed after 9 hours of movies already should be left that way, and the filler that is what is most of the Hobbit (and entire series) becomes too obvious knowing the ultimate conclusion before the beginning. Saving people from giant spiders and goblins isn't that heart-stopping when you know the entire world will be in danger one generation of hobbits later...and everything will turn out fine for mr bilbo, who ultimately is played off stage in the sequels.