maybe because the character of Smaug came from the works of one of the greatest fictional writers of our time, and fleshed out by decent writers into a film adapted version of himself, people who actually cared more about character, then say game makers who take there ques from comic books they read as teenagers.
Blizzard writers, while they use to have some effort in there characters, you know, when it was more about the story then the game, now its just about the game.