Who rapidly lost interest when the studio vetoed Bilbo piloting a giant fighting robot.
You see, del Toro was originally set to direct the prequels, but he almost immediately ditched the production. The perfect backup plan, Peter Jackson, was called in to replace him at the last minute. Unfortunately, Jackson didn't like del Toro's design choices and rebuilt everything from the ground up. There was absolutely no time for this; he had taken several years at the height of his enthusiasm and virility to plan out The Lord of the Rings trilogy but would have only a few months for The Hobbit films.
The result was that Jackson had to wing it throughout the entire production, putting actors in front of green screens and just sort of going from here. Things like "storyboards" and "scripts" were rare luxuries and he even had to turn two movies into three because he couldn't figure out how to shoot the final battle. If you think of The Lord of the Rings as a master chef preparing a fine meal, The Hobbit was a janitor at a hot dog factory found dead in a meat vat.
New Line Cinema
"Well... We already paid for the ingredients..."
In the Blu-ray release of this doomed trilogy, all of the behind-the-scenes featurettes sound like extended apologies. They talk about how tired Jackson was, or how pulling two movies out of his ass destroyed him. There are literally shots of him looking sad while people talk about how sad everything was. And, again, this wasn't some tear-down piece on a mean-spirited blog -- they included it in the bonus features of their own movie! These filmmakers did everything short of putting a Surgeon General's warning on the film that watching it could be hazardous to your happiness.