Now as for The Desolation of Smaug and Peter Jackson; well I have tended to default to the following question, "What would Tolkien think?"
Tolkien did live to see a film script and to comment on it (discussed in past Tolkien threads). The Zimmerman script was undoubtedly a bad one, unambitious and careless, and Tolkien's criticisms are appropriately blistering. But, three points of interest emerge. First, Tolkien had no objection to a film adaptation of The Lord of the Rings and presumably of The Hobbit. Second, he was well aware that certain cuts would have to be made and he was sure that in some circumstances outright cutting would be preferable. But what would happen if the alternative were to take place, where the prime narrative (Bilbo's growth and progression as a character) were to be downgraded, and at times play second fiddle to subsidiary narrative (ancillary material and minor/non-existent characters elevated beyond their established roles)?
Tolkien had this to say:
Letter #210.
In defence of Peter, Fran and Philippa, Tolkien was guilty at times (whether purposely or not) of ignoring basic axioms of narrative, certainly 'show, and dont tell'. On occasions Tolkien's narrative is unusually talkative, and ready to bypass major dramatic scenes leaving the reader to fill in the gaps. An obvious example from The Hobbit is Gandalf's disappearance. But therein lies the crux, writing a book is wholly different from controlling a huge budget, having to think of producing a return on investment, to consider popular appeal and so forth.
Are the inclusions damaging to the trilogy? Arguable. Do they harm Tolkien's legacy? Not at all. Is Peter's vision of The Hobbit the correct one? Highly debatable. It's certainly not my vision of The Hobbit, but what does that really matter. What matters is exposure and the films do certainly act as a gateway (albeit with preconceived notions) in to the Legendarium.
But above all, one man's imaginative genius has had the benefit of two lifetime's work (thank you Christopher Tolkien) and the varying visions of Jules Bass, Arthur Rankin Jr, Ralph Bakshi, Peter Jackson, Chris Bouchard, Kate Madison, to name just a few.
Onwards to The Battle of the Five Armies we go.