I think in combat some times there should be a moment where your enemy is at low health and you put your sword to their throat, then knock them away. Your enemies should also be able to do this.
If they knocked you out and left you crippled in the middle of nowhere...I doubt you would wake up in time to exact revenge. :shrug:
I doubt someone would just knock you out instead of just finishing you off and not have to worry about you later (especially if they where trying to kill you in the first place).