Why do superheros show so much mercy to the villains? I can see not killing them outright, at least not at first, due to some hero's code or something, but often they even go out of their way to save the villain from being killed by some other force or feel bad when the villain is harmed in some way.
In the end of Arkham City, Batman (SPOILER)says to a dying Joker, 'You know what the real funny thing is? If there was a cure, I would have given it to you.'. After everything that Joker has done, everyone he has killed, everyone he would kill if given the chance, Batman still wants to save him. Doesn't the countless lives saved by killing Joker outweigh the moral high ground of leaving him alive?
I was watching Spider-man the Animated Series the other day and during one fight Kingpin got hurt. An ambulance came to take him away and Spidey said something like 'it's ok Fisk, they'll take care of you, you'll be alright.' Wilson Fisk, the Kingpin, leader of all crime in New York and the man who has tried to kill Spider-man over and over, is actually comforted by Spidey after a scrape (which began with Kingpin trying to kill Spider-man with his six warriors)?
These aren't the only examples. So what is up with this?