There was a slight sympathy backstory given on Light about his dark descent with his father Soichiro Yagami being too busy to be with his children due to the crime rates increasing, and if the weight of crime rates over burdens a Pure Good then God knows what impression this was giving to Light at a young age seeing the world not being fixed much, and unlike Lotso who could just move on and not rule others over what happened with his owner, Lights situation with was going in the world was inescapable which lead to his downfall in being the monster he became.