I think this kind of writing makes a lot more sense, when even heroes can "fall from grace", if they make the wrong decisions at the critical moments, and then they can even lose their powers/blessings, and even better, get branded as a failure of a human being.
I think it's so stupid when in so many mangas the heroes can be the worst people there are, who just abuse their power, and act even worse than the demons they're supposed to be hunting.