>>114101563His character and personality, plus the fact that he operates mostly at night and utilizes stealth and deception?
Cause writers wanna reuse characters and not kill them off permanently?
Also, killing anyone would make a lot of people in favor of Batman turn against him. An average joe wont feel safe knowing Batman has taken it upon himself to decide who gets to live or die, even if he only does it to Joker.
There could be quite a few ways to write Batman dealing with Joker permanently, but writers wont do it.
