Co-producer Philippa Boyens addressed some changes made for the movie adaptation, especially the addition of a new character or two, something that could be seen as heresy by the literary community or Tolkien fans. Boyens said the story felt weighed down by males, so they created a female elf, being played by Evangeline Lilly and seen briefly in the footage.
Vox Popoli has the proper response:
What. The. Fuck? Tolkien's novels are a masterpiece. A classic. They define a genre. So Philippa Fucking Boyens decides she can improve upon them by adding a female character to do what, discuss tampons and boy bands? Does Tokenlass spend her screen time regaling the dwarves with tedious gossip about elves that none of them have ever met? Does she have sex with Borin before making a hypergamous upgrade to Thorin [...]
I wonder if Hollywood wanted to make Lawrence of Arabia today, then would a woman be included in the movie to, you know, bring that ridiculous "feminine energy"?