i never had the need and feel to have any empathy to villains, not just here but in everywhere
sure they had rough backstory, but that doesnt mean they are absolved of their sins whatsoever
if it does, then what's the point on charging criminals in jail?? does the law needs to hear their sobs story and they suddenly free of charge?? heck no. where's the justice then??
many people including author often forgot, they are criminals, they need to pay their crimes. but no, most likely still alive with limbs intact, not even a scratch. either they become an frequent enemy or just gone.
unless these people becomes a victim themself, they keep thinking criminals is nothing, not their business. but when they do become victims, they will cry the hardest
tldr i'd rather have them killed sooner and move on with the story