>>149875910
It's straight up because he's dark and serious and brooding and in stories with serious subject matter.
They can't rationalize how a character like that would also have such a cartoony premise like him not wanting to kill anyone ever, so they basically spawn two camps - one believes Batman should kill to match the tone and setting of his stories and character, the other believes Batman stories should become less self-serious so Batman himself will seem less ridiculous.
It is, quite unironically, secondaries who can't grapple with why people like the character in the first place.