Critical Hit Effects in GURPS

What?
I've altered the effects of critical hits in GURPS to remove what I perceive to be the unrealistic aspects. I've tried to give results that can be explained as physically happening in the game world.

Why?
I think I need to begin by looking at what critical hits are and why we have them in the first place. As I understand them, their purpose is to give us a mechanical way of representing outcomes that are otherwise below the game mechanics' level of resolution.

Critical hits have two effects:
1) They remove the defender's chance to defend against the attack.
2) The attacker makes a roll on the critical hit table and gets a supposedly physically possible effect with a low rate of occurrence.

In regards to #1: I don't see how the critical hit rates would differ based on skill. I'm not familiar with earlier editions of the game, but I imagine this was acting as a pseudo-deceptive attack before that rule existed. That skill is tied in with #2 seems extremely odd to me, though. I can't justify highly skilled characters experiencing those essentially random and uncontrollable outcomes more often. It seems strange that a critical hit, something external to the defender, removes the defense roll entirely. It's difficult to explain how a robot with reflexes a thousand times faster than a human's can fail to defend against one attack in eleven from a human swordsman, regardless of the swordsman's skill.

Now my major concern: The critical hit table in GURPS gives results that don't make any physical sense. What does damage in GURPS represent? Kinetic energy. It's what determines whether an arrow pierces a bronze cuirass and it's what determines whether a bullet pierces a tank's glacis. What, then, do the double and triple damage results on the critical hit table represent? Clearly they are an increase in kinetic energy. I find this incompatible with reality. Ten damage is 625J, nearing the upper limit of human muscles. Thirty damage is 5625J, which is well beyond anything the human body is capable of. A bow or gun, or a human's sword arm, don't function this way. I can't conceive of this result ever happening in an unpredictable manner. If my gun occasionally shoots for triple damage, then clearly I should be able to alter its mechanism so it always shoots for that amount of damage. If you look at Olympic athletes and the results they get at events, their muscle output is consistent, with variations of one or two percent. If human muscles, guns, lasers, and all other weapons outputted five or ten times their normal wattage as GURPS claims they do, this would show up in measurements of athletes and firearms.

The ability to ignore some amount of DR also makes little sense. It can't be explained as a flaw in the armor in anything other than a narrativistic sense; what if my armor really has no flaws? Does the critical hit travel backwards through time and cause the smith to work weak spots into the armor? Weak spots that can't be detected by even the most advanced instruments (for the DR of homogenous TL12 robots and vehicles are also halved).

Why would a TL11 war robot drop whatever it's holding because it was struck by a man with a sword? Why would this continue to happen after that model's next firmware update?

I don't believe these results are intended to explain the physical goings-on of the game world itself. The results they provide can't be explained in terms of the physics of the in-game universe. When using these rules, I am unable to achieve the desired sense of verisimilitude.

As such, I offer these alternatives:

The rules:

Critical hits no longer remove the defender's chance to defend. I am considering three options here. Option #1: no defense penalty, defender defends as normal; Option #2: defender defends at -4; Option #3: defender defends at half of the attacker's margin of success on his attack roll.

I think I prefer #2 here for ease of use, but I could argue for either of the other two.


And here is my new critical hit table:

3 You may change the hit location of your attack to any other of your choice.
4 Maximum Damage.
5 Your opponent can't retreat from this attack.
6 Shock penalty from attack lasts an additional 1d seconds.
7 Attack is at an additional -2 to defend against.
8 You get +3 on defenses against the attacked target until your next turn.
9, 10, 11 No additional effect.
12 Same as 8
13, 14 Same as 7
15 Same as 6
16 Same as 5
17 Same as 4
18 Same as 3