Funny, I never had a problem with this in a game where subdual damage is easy, cheap, and powerful (shadowrun). Generally speaking, the PCs never cared whether they killed the opponent or merely dropped them unconcious (barring squaring off against the cops, or the handful of bar brawls they were in - both cases where they did not escalate to dealy force if they could help it). I know the milieaux are different, but doesn't have to be a problem.
Being at 0 just means they are out of action - they are bleeding on the floor attempting to hold the blood in that's escaping from the stump of their hand could be a 0 HP status, but not immediately lethal. And that's within the realm of character decision - does he lop ff th hand, or stab in the chest?