I think there's a big difference between a 'tame' animal and a domesticated animal. I used to have a pet possum that was pretty tame, and the way he acted reminds me of the way most snakes do; they're fine until something new or 'scary' happens, then they immediately revert back to acting on instinct where a cat or dog might look to you for help.
I do wonder how genetically different BPs generally are from their wild counterparts though. I know they're not TOO different, but it'd be interesting to know.