Pat, I know that's a rhetorical question, but let me answer.
Because he is who they invited. And he is constantly invited to be on these shows because the media has an agenda. McCain fulfills that agenda very well.
What is that agenda, you ask? Well, you didn't ask, but I'll tell you anyway...
No less than the triumph of socialism, the defeat of the conservative political movement and the spread of atheistic, earth-worshipping, government-dependency of the less than elite-class of the American people.
The media consider themselves the elite. Along with their like-minded political betters, they want to be able to dictate to the rest of us everything and anything.
McCain is a vain idiot who just never realizes that he is a tool.
I thought that the election of 2008 would prove that to him, when the media turned on their favorite "Maverick" and tried to make him the Second Coming of Darth Cheney, but he was too stupid to comprehend what was going on.
But his criticism of conservative thought and action is still very useful to the agenda, and therefore he's a perennial invite on these shows.
No less than the triumph of socialism, the defeat of the conservative political movement and the spread of atheistic, earth-worshipping, government-dependency of the less than elite-class of the American people.
You forgot baby-killing and boy-raping.