David Foster Wallace did
a really great profile of a conservative talk show host, John Ziegler. He managed to make the point, very delicately and coherently, that talk radio is never about politics. It's about entertainment and money. And the reason why most talk radio tends towards conservative politics is that it is easier to make more entertaining.
Another one of those funny points where seeing it (entertainment) as what it's not (journalism) just leads people horribly, horribly astray.