The Hobbit's gory battles don't just pad out its run-time. They contradict the story's message about mercy.
"True courage is knowing not when to take a life, but when to spare one," Gandalf tells Bilbo in Peter Jackson's The Hobbit: An Unexpected Journey.*
Gandalf's homily doesn't appear in Tokien's original novel The Hobbit. Still, the sentiment has some textual support. Specifically, in the book, Bilbo, having discovered the magical ring of invisibility, has a chance to kill the sneaking, loathsome creature Gollum—but instead spares him.
Bilbo almost stopped breathing, and went stiff himself. He was desperate. He must get away, out of this horrible darkness, while he had any strength left. He must fight. He must stab the foul thing, put its eyes out, kill it. it meant to kill him. No, not a fair fight. He was invisible now. Gollum had no sword. Gollum had not actually threatened to kill him, or tried to yet. And he was miserable, alone, lost. A sudden understanding, a pity mixed with horror, welled up in Bilbo's heart: a glimpse of endless unmarked days without light or hope of betterment, hard stone, cold fish, sneaking and whispering. All these thoughts passed in a flash of a second. He trembled.
Bilbo then (in both film and book) leaps over Gollum's head, leaving the creature despairing but unharmed. Later, in The Lord of the Rings, Gandalf suggests that Bilbo's pity for Gollum "may rule the fate of many." At the end of Rings, it is ultimately Gollum who, inadvertently, destroys the ring and saves Middle Earth. Mercy is ultimately salvation, and Bilbo's decision not to use violence is at the heart of the quasi-Christian moral order of Tolkien's world.
If Jackson meant for Gandalf's comment to highlight Tolkien's nonviolent ethic, though, the rest of his film undercuts it—and, indeed, almost parodies it. The scene where Bilbo spares Gollum in the movie comes immediately after an extended, jovially bloody battle between dwarves and goblins, larded with visual jokes involving decapitation, disembowelment, and baddies crushed by rolling rocks. The sequence is more like a body-count video game than like anything in the sedate novel, where battles are confused and brief and frightening, rather than exuberant eye-candy ballet.