Well, by the same logic, throw HP out the window altogether. After all, it's an artificail and arbitrary Hit Die that generates it. Right?
I'll preface this gripe by saying that (A) I generally come off as an ass at times like this and it's not intentional and (B) I think changing rules before you play them is incredibly shor-sighted, but you folks have your own games and can run them how you see fit.
By saying "bypass armor" I meant that AP functions to "chop through" DR. This doesn't ignore armor, that's why ther are Finesse Weapons.
A finesse weapon in the hands of a character capable of a sneak attack can deal an enormous ammout of damage, and probably at a lower level, causing Massive Damage.
Yes, an AP1 guy and an AP7 guy cannot beat through a DR8 armor guy, no matter how much they pound. Except, the DR is only a reduction in damage and if they do enough damage, they can still bring him down by attrition or smart fighting. As a matter of fact, if one of them lands a blow that deals 28pts of damage, the DR8 guy has to make a MD save...doesn't matter that they couldn't chop through his armor.
If you don't like the static 20 for MD, look back through this thread where someone suggested using CON. That makes it more variable. It doesn't work for monsters tought because some of them have metaphysical properties that increase thier FORT saves above what their CON reflects and vice versa. Ghouls are only CON 13, which is crap, but they have a +6 FORT. This would give a Ghoul a MD thresh of 19. If that disparity exists, adding the two together seems to work in principle, although I've not tried it yet.
Crits facilitate MD, but they should not be the only way to arrive at MD or you limit the number of occurances of it severly. AP as a damage add isn't a fix, it's ignoring the function of AP and DR in the game.
Here's my beef: Each time 20+ damage is inflicted on armor it's DR is reduced by -1d4. So, not only does such a blow force a MD Save, but it also reduces DR. It should probably be Crits that reduce Armor DR thereby making total damage above that value, and thus MD strikes, that much easier.