A toggle option would solve all problems. I have no problem with gore as long as it's not excessive like in gears of war. I don't want spray blood either. Besides if it was included based were you hit you'd pull off insta kills left and right.
I would like to think the skill (level/attributes, etc.) of the person you're fighting would impact their ability to block, dodge, take hits, etc. I understand there are some people who are really dead-set on "this is an RPG, it's all about hit points, no insta kills" yadda yadda yadda...
I don't disagree with this concept. But in Oblivion (and other ES games too, correct?) if you executed a sword strike, or arrow hit
while sneaking (and your skills were high enough), it was *GASP* an insta-kill.
I think once you work someone's health down through melee attacks, magic, etc., there should be a chance for a beheading or cutting off a limb depending on the strike you execute, location of the body, the deterioration of that place on your opponent's body that you strike, and some general randomness. This should happen even if it's not the last person you're fighting (with Skyrim it appears the slow-mo, kill cam happens with the last guy you're fighting), but I do agree that the slow-mo should only happen on the last guy you kill.