.
I cannot IMAGINE why. It makes no sense at all.
No. It was smart politics and a good move. You never, ever put someone on the ticket that outshines you and steals the show. Kaine was a masterstroke. He is able to step in and do the job if needed, yet he doesn't have to bring anything to a ticket that is going to win anyway. It's sad only to you, a good strategic move to the rest of us.