I think that if you polled children, somewhere north of 99.9999999% of them would say "the dragon is the bad guy!" in The Hobbit. Let's not get too pedantic. The Hobbit clearly has themes that resonate with adults and outside of the core story, that is what makes it Fine Literature(tm), but it is a fetch quest with a boss monster at the end.Smaug isn't the antagonist. He's an encounter. Try again.
The Hobbit is a perfect example, really.
But if you KNOW Sauron and Morgoth are out there, and in Middle-Earth this is basically THE DEVIL running around to some extent, it becomes very difficult to adjust stakes below this level. Do you think RoP is NOT gonna reference how destructive the One Ring will be, or hint at the wars to come? These big bads really adjust the scope of evil that audiences expect.
Could you make a nice anthology series pulling the smaller stories from Tolkien? ABSOLUTELY. Can you hang a BILLION DOLLAR epic on them? Highly doubtful.
I hope they build enough real shit that some small crew can come in, borrow assets, and make these side stories on a shoestring budget. But I don't think Amazon has access to really any of that stuff.
I dare say there is no market for a story of a meek hobbit, hen-pecked by his shrew of a wife, that decides to strike out on his own, leaving his mewling bratty kids behind, and becomes a pirate on the high seas with random adventures that in no way relate back to the primary struggle of elves, kingdoms of men, and The Enemy.
Fuck....now I kinda want that!