I haven't seen "I am Legend", as I am not a fan of horror flicks, but I am very interested in how all forms of media are used to convey a message. I would certainly enjoy the original version of the book, I really dislike this attitude of "good v evil", demonizing your enemy.
Pocahontas, the Disney version, had a very good message about this, when "The settlers arrive as John is about to be killed. Pocahontas throws herself over John, telling her father that if he kills John, he will have to kill her as well. Powhatan is persuaded, and John is freed. Ratcliffe orders the settlers to fire anyway", at this point, the chief says "who are the real savages".