Eh, that would be nice and all if most of the "dead" characters'd had much of a choice in the matter. Xion and Roxas certainly didn't; both were pretty much forced to give up their existences. They couldn't have escaped their fates no matter what they did. Roxas was literally beaten unconscious so DiZ could drag him into Virtual Twilight Town. You call that a choice? What Roxas and Xion did wasn't sacrifice... it was pretty much giving up because there was nothing they could do that would make their situation any better.
BINGO! There was never a choice for these characters. It was either Bad Ending No.1 or Bad Ending No.2. They lost the moment they were born.
Like hey to each their own but arguing that they had choices when there was none only adds more insult to these characters.