Once again... The game has a finite amount of exp so why have a level cap? It's not like games where you can grind for an infinite amount of time
Please stop and listen to yourself, you are acting like every single person will be playing the way you do.
Not every Player will be sneaking and unlocking every lock, find every quest do every single little thing that gives them that 1 extra exp. A game developer whom has a plan for your character that you created and reached level 12 to be imported into their sequel can not have a character that cheese the game by Soloing and gaining the bonus exp boost that probably gets you to level 15, therefore bypassing 3 levels of awesome new spells that you will get, new stats, new attributes that they might possibly put in their sequel. And then have Players like you , posting threats on how come their new game is so easy even on Hard or Path of the damned, because I am level 15 and I cheesed my way there but its not my fault, its the developers because you allow it to happen.
Having a level cap of 12 allows everyone to start at the same point once the Sequel comes out.
If you still don't understand, even with finite EXP available, not everyone will get all the Exp available, some people who played the game blind, at best they might only accumulate 75% of the ExP available. Then are you saying that by not exploring everything the Gamer should be punished?? Should all gamers play the game the same way, do I HAVE to explore everything , everywhere, who dictated that I have to explore everything everywhere to experience the game I bought like everyone else. Game developers have to assume that the majority will reach 75% , for those that reaches above it, they are more prepared for the fights, they have all the tools available for future encounters compared to those that isn't, but aren't punished other than having the fights lasts longer.