Who is Middle America?

Why is it that when a TV journalist decide to take the pulse of the nation they inevitably head to the heartland to interview a salt-of-the-earth farmer type even though they are just about an endangered species rather than the silent majority? Kung Fu Monkey has got a great post about this. Apparently there are 2 million farm and ranch workers in America. As opposed to 4 million players of World of Warcraft. Why is it that our conception of who the Middle Americans are have not changed with the times?