A lot has been said about role-playing, immersion, whether we should be able to play as a Ghoul, Super Mutant, or what not, and whether playing as a human is boring. To me, the Sole Survivor of Vault 111 is not the mom or dad, looking for their abducted child. To me, the Sole Survivor is a monster. Not an evil monster, but a monster still. A monster whose existence is filled with just one purpose: to feed. But unlike a vampire, who in most lore-driven scenarios is deemed to be dominated by its need for feeding on blood, the Sole Survivor feeds on XP.

XP is the beginning and the end, the diving force of all. It is a food, it is addiction. Whether you live or die depends on how much XP the sole survivor will get from the outcome. Everything that moves, or even if it doesn't move, is a bag of XP and sometimes loot. The Minutemen told her "you did this for nothing, just to help us." Poor fools, she did it to feed, she did it for XP. Again, and again.

And just like people enjoy variety in food, the Sole Survivor enjoys the XP to come from variety of sources. This is why you, little Dez, may live another day.

Kotor 2 is one of the only games i know of where the player character gets stronger from killing and questing is explained instory.

One of the things that I kind of liked about Mass Effect 2 was that you got XP exclusively from completing quests, and there were no infinitely repeating quests. So you couldn't grind, even if you wanted to. You'd just be playing more game.

Repeatable quests are one of the best features of FO4 IMHO. My post wasn't a complaint about that.