Heroes and protagonists

I am watching the commentary on Die Hard -- the subtitled commentary, not the verbal one. I've had the DVDs for years but never watched this commentary. However, I'm on a Die Hard kick and thought I'd see what it had to say. It's very will done, interweaving comments from the director, writers, actors and reviewers, etc.

At one point, while discussing the character of Hans Gruber (Alan Rickman's first film role) De Souza (one of the writers) comments: If you want to get technical, John McClane is really the antagonist of the movie. The protagonist of the movie is Hans Gruber. People mix up hero, villain, protagonist, antagonist. This is where most screenplays go wrong. The hero isn't always the protagonist. The villain isn't always the antagonist. The protagonist is the person who starts the ball rolling, the protagonist of Die Hard is Hans Gruber when he decides to rob this building. You write a movie like this by asking, "What does the protagonist want? What does he have to do to get it? What does the antagonist do to thwart him?" This film works so well because everybody working on it knew the difference between the protagonist and hero and because we always go back tot he protagonist to see what he does to offset the counter-move by the antagonist, who is the hero!

( This is an interesting concept because )