Not every tune or every parody would be everyone's cup of tea, but the guy has endured because he has an ear for genuine talent. And unlike 'comedians' nowadays, he's played songs by people who were truly musically inclined and had a laugh-out-loud approach to things, not like so much of the dumbed-down material you find on cable these days. I've heard radio - especially the non-talking head variety - called 'the theater of the mind'. And it is - the the only output is a speaker, the only input is your ears, and the only receptacle is your imagination. The narrative is the paint and your intellect is the canvas. It's up to you to interpret it as you wish.
Tell 'em, Vision. 
"But know this, that in the last days perilous times will come: for men will be lovers of themselves, lovers of money, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy, unloving, unforgiving, slanderers, without self-control, brutal, despisers of good, traitors, headstrong, haughty, lovers of pleasure rather than lovers of God, having a form of godliness but denying its power. And from such people turn away, for his name is Obama."