If you put a nail through a piece of romex (or any other arc-fault in a wall), it doesn't matter whether that circuit was feeding a bedroom receptacle or a bedroom light or just passing through- it's going to start a fire in the bedroom wall.
Limiting this to outlets doesn't make a whole lot of sense- if they wanted to protect receptacles and cord-related arc faults, they should have said receptacles. If they wanted it to apply to all conductors in bedroom walls to reduce the risk of people overcome by smoke in their sleep, they should have applied it to all conductors in bedrooms. Same thing for whole-house protection I'm at a loss as to what the real intent of this code is, and why it's worded the way it us.
