When it comes to stealth games, the good ones anyway, there are always a wide variety of strategies for each and every mission. Some players (me included) like to sneak in undetected and leave nothing more than a couple of guards with headaches in their wake, others prefer to instead set the entire building on fire and dispatch all of the guards with ruthless efficiency, and others yet prefer to carefully thread the line between sneakyness and stabbyness.
Trying to create a game that equally balances out each of those playstyles is nearly impossible, because what one side might find fun and engaging the other side will see as a living nightmare. The only real way to make this work is to allow the players a way to create their very own difficulty settings, which just so happens to be exactly what Dishonored 2 devs are planning to do!
Through a patch that's set to arrive next month Dishonored 2 will get a New Game + mode for those looking for a true challenge, but also the ability to create your very own custom difficulty. The details are currently scarce, but if Arkane Studios allows us to even slightly modify enemy AI and patterns this could quite possibly add a ridiculous amount of replayability to an already lengthy game (depending on your playstlye anyway). Just imagine what sort of 'challenges' you could create if they only gave us the ability to mess around with enemy detection ranges!
On a somewhat unrelated note, if you're finding it difficulty to be excited about this new patch while you're still suffering from framerate issues and frequent crashes, there is currently a beta performance patch available on Steam. The full version will be coming at some point next week, but if you just want to get on with your playthrough in peace as soon as possible you might want to check it out and see if it helps. Good luck!