@ NinjaSteave: You are right, my suggestion is too immersion breaking. It may be a good idea in a mindless action game, where the player has several options to make his life harder however he likes. I do not have such a game, but I think I saw something where you have tons of options to make the game harder or easier for you.
I aggree that the most important factor for possible rewards should be how happy is the quest giver with the result of your actions. Please note that sometimes the player himself can be the quest giver. The player does not only exist to do what others say. In an immersive world the player character is a person who has some goals of his own. Sometimes it may be wise of the player to ignore the wishes of somebody else because the players himself profits from doing so. The game should somehow react if the player is nice (up to being lawful stupid, like always doing what others say no matter how dumb) or selfish (up to being evil stupid, like killing and destroying things for no reason).
@ Neonivek: As I have written before, most games became more boring once you hit max level. Many players want to get stronger during the entire game.
In Pillars of Eternity many players complained that they hit max level too early. Some of them created a mod that reduces the exp you get and they dicussed if 33%less or 50%less exp is the best value.

Prof. Dr. Dr. Mad S. Tist

World leading expert of artificial stupidity.
Because there are too many people who work on artificial intelligence already