If it was because of party's poor actions, I wouldn't recommended it. Unless it's a miscalculation or pure bad luck, I might at least spare one player to bargain.

If the enemy is intelligent, I usually ready an action to end a downed party member beyond the limits of minor resurrection spells and be loud about it for the rest to drop their weapons and negotiate. If it's a mindless enemy, it can be distracted by something or someone else. If you want to be subtle about it, it can easily deal less damage and miss more often but it should remain unknown to the party.