The McCain camp thinks that his maverick-ness is an asset. (Let's put aside the valid argument about whether or not he even is a maverick for the moment.) As soon as it was announced that Palin would be the VP pick, conservative pundits and surrogates lauded McCain for taking such a big 'gamble' and 'risk'.
Add this propensity to buck the system and his well-known reputation for being bad tempered and you gotta wonder ... Do we really want this guy as Commander-in-Chief?
I really don't want a President that takes gambles. Let's think back to 'bomb bomb bomb Iran' and his bellicose oratory towards Russia. Are we really going to be a safe with an angry person who likes to take risks and gambles? Seriously?
I would want a stable, thoughtful President who isn't afraid to take some risks, but isn't going to go completely and utterly out-of-the-box? We are dealing with the lives of our soldiers, as well as our the lives of every citizen. This isn't a game.
By choosing Biden, Obama has shown that he makes serious decisions wisely - not throwing a Hail Mary in order to win.