The key issue with the Hobbit is that it’s just a series of adventures. Adventures make sense for an episodic medium, like TV, but not so much for film. Watching just the first installment, it was like five or six mini-stories and, while each was cute and fine, it’s a bit tedious, like someone taking five or six arbitrary episodes of Seinfeld, throwing them together, and telling you, “This is part 1! Of a trilogy!” The pacing just doesn’t work. If you watched that, no matter how much you might like Seinfeld, it would clearly present as “some random TV episode quality mini-stories that were tossed together.”
I’m sure that they could have turned the Hobbit into a trilogy, but you would have to rewrite almost the entire thing and add a proper set of three movie-sized tales that built up what would come later while still being internally full and satisfying in each of the three parts. Or, alternately, removing nearly all of the adventures and just dealing with the main storyline in a single film.
Given the general lack of deep love for The Hobbit, I suspect that they could have gotten away with the former and it’s a shame that that didn’t go that direction.
And, of course, the cartoon physics through the whole thing was just horribly ill-conceived. While I can somewhat understand the desire to bring all of The Hobbit to the screen - if you’re a fan and someone has given you the money to do so - there’s really no excuse for the directorial decision to do the action sequences like that. That’s just channeling George Lucas.