True. If they were to get their old hearts back, they'd be regular humans. Perhaps they want to optimize how complete they can be (getting the best heart with the most power, stuff like that).I never quite understood it either, back when playing KH2.
I suppose they were just thinking that KH would make them complete in a different way.
I suppose it is much like Xehanort's Heartless, who became a complete being by stealing Riku's body instead of his own.
So there are unbirths after BBS. I thought there wernt. Oh well, you know your stuff I wont disagree.
I don't recall that being mentioned anywhere, only that Heartless and Nobodies don't exist in BbS.