|No, not this critical hit table|
Incidental navel-gazing: I have been finding that the more I learn, the more I question conventional wisdom. I think I'm turning into a D&D hipster.
For this, I denounce myself! ;)
The only figures who are involved in every important fight are the PCs and their allies. Therefore they will be subject to far more numerous critical fumbles and take far more numerous critical hits than any other figure.
The balance to this - the critical hit - is not enough to satisfactorily balance the additional harm the system does to their chances. While small, this disadvantage will add up over several fights.
The solution I came upon is to give only the fighting-man the critical hit. A fighting-man who rolls the 20 drops his man to 0 hits immediately. Like hitting a home run - that at-bat is over, in his favor. It means mooks chump negligibly quicker and he has a chance to slay the nigh-unslayable dragon.
Don't like not getting the crit? Play the fighting-man!
And yes, one-shotting a dragon is pretty awesome (if possibly anticlimactic.)
The larger point is this: combat can be exciting and satisfying with few rules. You don’t need the HERO System to get it right. In early D&D especially, presuming general competence in adventurous men and adhering to simple rules like move rate, morale and attack rolls versus armor class make for perfectly satisfying combat encounters without the gimmick of a critical hit table.