Thank you for your suggestion, but I'm afraid I disagree with your reasoning. In my opinion, averaging the movie ratings isn't a way to determine how much you like an actor, because our relation to actors isn't mathematical, it's emotional. Many actors we love simply because they're good looking. There's no way a program can predict how much you'll like an actor based on your movie ratings. Movies generally have many actors, some good, some bad, the story is also very important, the directing too. It's impossible to relate your movie rating to how much you like an actor. Maybe it could work a little with directors, but certainly not with actors.
Anyway, what would be the use of predicting how much you'll like an actor? To decide what movie to watch? For that you already have the movie recommendations...