The Road: The Movie vs. The Novel

Started reading The Road this morning and just finished. I just couldn't put it down. Cormac McCarthy's fast paced syntax and in your face word choice mesmerized me. Actually having seen the movie first really added a new perspective to my reading. I appreciated McCarthy's detail, and the elements of plot which were furthered developed in the novel intrigued me. So, why in the movie, was there so much more blood and gore? I suppose because blood and gore sells. It certainly wasn't needed, and I think that the excess blood actually overly colors the greyness and despair facing the two main characters.