Maybe because he's a joke?

Seriously: Kerry on Comedy Central:

When John Kerry decided it was time to do his first national TV interview since the Swift boaters for Bush launched their attack on the senator's Vietnam War record, he did not choose CBS's "60 Minutes," ABC's "Nightline" or "NBC Nightly News."

Kerry picked Comedy Central's "The Daily Show," where he will appear tonight in an extended interview.

No word on whether he'll be wearing his "magic hat."