Why are CN readers so bloodthirsty?

I dropped MoE for a while so I don't understand but it's probably bad and it will surely be because a hundred chapters aren't enough to end the story nicely 

Because the amount of times someone has been let off just to only bring back someone stronger to 'avenge himself' in the fight they started, are too many to count. 

Generally there is two reasons. The first is that the MC has shown his willigness to kill off all the enemies and their families and then just doesn't for one group and then a few scenes later the villain who he let off comes back and causes more trouble for the MC often involving the MC's love interest/s. Or second the MC has let someone off in deference to x old master when he is clearly in a position to rid them from the world and it seemed like he was just wasting time until this old master has appeared. This is especially annoying when they usually show no respect or said villain doesn't repent which happens to be most of the time.
This is memeing XD or because they are very very annoyed that someone has been allowed to live for so goddamned long holy fuck would you just stop him so he stops trying to rape your wife goddamnit man! 

This brought whole different can of worms. Since this is still unresolved issue of how to interpret laws between natural laws "by spirit of laws" and formal laws "by black and white letters" traditions. Obviously, you and I are on different sides of the gulf since my beliefs are "The ends do not justify the means" and there are always different ways to do things. So let's not get dragged in this quagmire unresolved yet by even the best legal minds.
In the case of general Chinese novels here, they were more likely went out their ways to wack more people first, long after the very first justifiable self-defense, and that hardly okay on both your and mine books, I presumed? 

Eh, what's the point of obtaining power if you can't do whatever you want?  Why not just stay weak and be a pushover for the rest of your life?  Also, in many of those novel's situations, anyone else other than the MC would have been dead a thousand times over.  Forgiving others because you're powerful enough that they can't do anything to you is dumb.  If you're the weaker one, do you think they would spare you?  

I'm still wondering how fast their reproduction rate is compared to the mass killing that is done by almost anyone in that world. 

Just so. I hope it doesn't go full MEN in the last hundred chaps. 

In CN novels if you leave 1 person alive, they multiply like rabbits and come back with a full clan to kill your family while you're in closed door cultivation.

That's why