I mean if the villain's redemption is well written then typically the guilt from their past actions is the punishment for said actions, and their current actions are largely focused on atonement and reparation. That sort of thing often makes them even more relatable because while not everyone has killed another person, everyone in the world has hurt someone else at some point, maybe unintentionally, maybe unknowingly, maybe due to extenuating circumstances or their own trauma, or maybe because they were just a worse person at the time. Does that mean they are never allowed to be a better person and must eternally suffer for all the wrongs they've committed? Is it not better to encourage their goodness in the present than to forcibly drag them back to when they were bad over and over again for the sake of vindication? Does society really benefit from that sort of thing? And what if they end up saving more lives than they've taken? Something to think about.