Rules do have to bow to logic sometimes.
i agree completly with logic playing an important rule, but how much logic can you apply to a magical attack that sucks the life force from a creature
My theory of logic on the idea was, I am going to be using a rapier (kinda cheesy if the spell can crit with the weapon but I won't complain if the DM takes it away or limits it after a single combat) so a crit with a rapier would be piercing through the body to a vital organ, more sensitive/important tissue, or a vein/artery, so vampiric touch (assuming it works like a magical syringe) would be able to pull more life force from this vital area then say stabbing their thigh.
As i believe the reason spells can crit when an attack is made is because they can be focused on more vital areas, but with a weapon of more accuracy to hitting vital areas it can be focused even more directly into the vital areas?
Had the spell been an inflict wound spell it would inject the "poisonous" negative energy directly to the area.
Had the spell been shocking grasp it would directly shock the tender area with electricity causing spasms (and i can only assume much more pain) in the muscle, nervous, or circulatory system.
if your goal was to kill someone quicker would you rather shoot tazer prongs into their heart or their calf? Would you rather inject a syringe full of potassium into a major blood way or their arm?
Not trying to get aggressive with my idea just attempting to explain my view on it and looking for feedback, thanks again by the way.