Guess that's the reason why Nier has mechanics around having her dying over and over again to the player's benefit. It's supposed to be a retribution for her past deeds.
Actually, it's in reference to the fact that the only thing she has to give is her life. She has no real talent and can only manipulate and transfer her life-force. Nia is not on a path to redemption, but is rather a ticking time-bomb. She unknowingly sacrificed her capacity for love and empathy in exchange for forbidden knowledge, causing her to become a dangerous existence.