Okay, having just finished my second playthrough of Knife of Dunwall, here is a thing that really bugs me:

The low/high chaos distinction not taking into account what you do to your targets makes no sense (the formula is less than 20% of all NPCs dead to get low chaos).

Corvo is a trained assassin on a quest for revenge. It makes sense for him not to kill people who aren't his target, and it does make sense for him to orchestrate the downfall of his targets for poetic justice. What doesn't make sense is that the result for being entirely nonlethal and the one for getting in, killing your target and getting out without ever being spotted is exactly the same wishy-washy feel-good ending.

Knife of Dunwall ending spoiler, in case you finished the core game and not the DLC (this spoils both endings):

This is even more flagrant for Daud. Billie Lurk's subplot revolves around her trying to make a play for leadership of the Whalers (never mind the fact that this doesn't really make sense, since Daud's Outsider mark is the only reason they can teleport). The ending is entirely binary: did you go high chaos? She is unrepentant and fights you. Did you go low chaos? She surrenders to you after confessing.

Why is the person trying to oust you as leader of a band of mercenary assassins impressed by you going out of your way to not kill your targets?! That makes no sense whatsoever.

It's even dumber when you consider that the Outsider tells Daud that he's walking a knife's edge between redemption and damnation multiple times - this isn't a knife edge, it's just the same binary good/evil morality.

Here's how it should have ended: went nonlethal? You've gone soft and Billie turns on you. Went high chaos? You've gotten sloppy and Billie turns on you. The only way Billie shouldn't turn on you is if you go low chaos and kill your targets, thereby proving that you've still got what it takes to lead the mercenary assassin Whalers.

Maybe an argument for not killing Rothchild unless you spoke to Ames, since you weren't paid to do it - with Ames asking you to blow the warehouse, but Daud refusing.

e; basically, all of my problems with the plot boil down to the fact that low/high chaos is entirely binary, and there's no third state that you would get for only murdering your targets - medium chaos exists but is just obtained by having a mix of high and low chaos and shares the high chaos endings, and killing only your targets will always give you low chaos.

If they'd done that and given the game a distinct ending for only killing the targets, it would be a lot less stupid.