My question as well. Of course, they've already butchered the Hobbit and turned its concise sweetness into multiple epic screen extravaganzas, so stand by for Lord Of The Rings II - Revenge Of The Orcs with a multiracial cast and a few gay and lesbian subplots. Gosh, I wonder what Chris Tolkien is worried about?
Looks to me like Jackson actually backfilled the Hobbit with material from LOTR, both the Appendices and the main story—after all, Gandalf’s story as to where he went was expanded in LOTR, including finding Thrain in Dol Guldur (something that is in the Desolation of Smaug extended edition). Rewriting Azog as a main character turns it into “alternate universe” and really ought to be left to the fan-fiction sphere, but it seems (at least to me) that Jackson wanted to evoke the atmosphere of the Fellowship being hunted by the Nazgûl.
As for the “sweetness” of The Hobbit, even Tolkein expressed regret that the story was not more LOTR-like, and had to rewrite Gollum’s part in the “Riddles In The Dark” chapter to match what was going on in the later story.