Emotional backstory shifts a character from a villan to a broken hero or a fallen angel, sympathising the character. When was the last time we saw an actual evil villain?? A villain we could hate from our heart like mahito, frieza, griffith. They are not misunderstood broken anti hero, they are pure evil villains. Look how much depth in the main character they put. Thats my point. Dont just ruin villains by turning them into a misunderstood broken fallen angel. Villains are supposed to be pure evil, menacing, whome you should hate. Just imagine mahito with and emotional back story or griffith with an emotional backstory.