"It's one of those... 'complete experience' mods that many gamers so love, letting you link your minter up to the gameplay. It's a later addition - considering that the sort of full body pain mapping settings that you would naively implement didn't have much of a market outside of those for more traditional sexual play sims due to the intensity of it or the lack of meaningfulness to the system when dialed back, they got the bright idea to map it to exertion alone. The feedback of an overstretched arm, the build up of the strain from a long battle, or worn feet from a journey, rather then the feedback from the wounds or anything like that. They kept the tunability, of course, but the ability to follow along the struggle of your character is something I personally found fairly powerful, even if there isn't the same sense of stakes you get when you play the more hardcore titles."