Twilight Gap
Member
I think there is never going to be any confirmation on why that is the case but I imagine that it is that way because both Sony and MS have absolutely no interest in allowing cross console family character sharing.
I would guess that Bungie and Activison could care less about it and instead would be happy to have cross console family sharing because it might motivate more people to double buy Destiny to play with friends on both PS4 and X1.
Sony and MS on the other hand want to lock you into their ecosystem.
i'd have double dipped ages ago if i wouldn't have had to create separate accounts and characters.