Why are superhero villains portrayd as sympathetic villains when a superhero kills someone they care about despite the villain themself murdering nameless innocents?

For hypothetical example; Father/son duo are criminals, harming, killing, and stealing innocent civilians. Superhero fights them, resulting in the father dying. Son is now portrayed as a sympathetic villain because all he wants is to avenge his father... despite all the fathers of children they murdered whilst comitting crimes.

Side question; do you feel sympathy for the villains portrayed like this?