He blew up a cancer hospital for God sake, he needs to die, I don't know why he holds back.
Batman has foolish, dangerous, and unrealistic notions about not using knives, guns, or other effective weapons appropriately.
It'd end the fun.
Batman would end
Then he would no longer be the Batman.He will be just another rich thug wearing a costume and punching people around
to do so batman would give the joker what he wants
If Batman is adequately trained to fight crime without needing to resort to murder, then it makes no sense for him to kill the Joker. In case you're wondering, I'm a pacifist who believes in killing as few people as possible.
The entire point of Bruce Wayne's Batman was to convey a message to the citizens of Gotham that truly good people do exist. Despite the horrors committed by the human waste that comes with every urban area, despite corruption in the police force and the other higher powers that be, justice can still win out in the end. One does not need to become a killer to stop one. One needs not sacrifice their own morals and dignity just to "make 'em pay". Revenge doesn't work, and Batman knows that it doesn't work. It also does nothing to raise morale or teach anyone anything of value. If he were to give in to the primal impulse for vengeance (which is precisely what Joker wants anyway) he loses, for once and for all. No longer a hero, he would become exactly what it was he labored for so long to stop.