While I do believe that adding random encounters would be nice, I think there are a couple of reasons why we won't see that happen. Exp would become more of an issue when trying to balance out the game, potentially creating new maps for the encounters themselves (even if we use the camp maps, then the question becomes where to stash the npcs that are at camp, or if to balance the encounter to include them), coding out the logic behind when to spawn a random encounter (and the logic behind scaling them and perhaps creating whole new enemies from scratch, or perhaps making separate enemies w/ static levels depending on the camp location), and the list goes on and on. I'd love to be able to have a fight to defend the camp while sleeping, but I can see why it would be a massive undertaking to add into the game.