* NOTE: I am something of a difficulty fetishist (though not on the first couple of playthroughs). But even I realize that it's a side challenge that the vaaaaaaast majority of the user base not only won't care about, but would be upset to find out that things were cut just so folks like us could scratch an itch.
By the way, it would be extremely interesting to know what percentage of players do more than one playthrough (you mentioned "first couple", and this caught my eye). In my view, PoE 1 had a replay value of exactly zero: there was nothing random in the game, and the world was totally static except for the choices you made as a player.
I really liked playing the game, but having got to the end, I can't see why I would ever want to start another game. (No criticism implied here.)
Different builds and different outcomes for the endings/sidequests that you didn't see the first time.
From what I also know, there are going to be NG+ options as well to add complications or bonuses for another playthrough.