Bingowings said:
Wouldn't Luke be a bit of jerk to extend that generous level of forgiveness to the man who killed his dad, killed his mentor and tortured his friends and not to the little old man in the bath chair who saved the galaxy from red tape, child indoctrination by wacky celibate kung fu monks and corrupt politicians?
LUKE : What are you doing with that poor old man?
VADER : Well I was going to throw him down this really convenient death-pit but if you are happy with him tazing your ass...?
A true Jedi does not take revenge. That's the point. And it would actually be brought out more clearly if Vader was not his father. Does that mean a whole lot of people would think Luke and the Jedi complete wimps? Yes. But they clearly do not share that morality, and they clearly think that revenge is a good form of justice.
...which is anathema to Jedi philosophy.
...which is the point the Saga is making.