[personal profile] sanctaphrax 2016-02-16 06:44 am (UTC)(link)
Since the big comic worlds are insane and stop making sense if you think about them too hard, it's generally best to treat the characters as representations of real-world people and ideas.

In the real world, vigilantes killing people is pretty much always a bad thing. So by analogy, Daredevil killing Bullseye is treated as bad.

The nature of the comic world negates the reasons that vigilante murders are bad in real life. But it also negates the reasons to kill someone like Bullseye. Sometimes the narrative twists to turn superheroes who kill into monsters, sometimes it twists to make killing morally mandatory.

It's all rather hard to take seriously. So the real-world-analogy approach tends to predominate.