Consider this: At the nitty gritty, every character in this system has 15 hit points before being disabled.
Two characters of equal ability fight. Both have a +2 Strength , Constitution, and Dexterity modifier, so the advantages of the respective abilities cancel out. Both wield daggers 1d4 damage. Neither wears armor. A single attack roll could result in a miss or from 1 to 23(!) points of damage. (Assume your attack bonus is equal to your defender's defense bonus. If you roll a 20 and your enemy rolls a 1, you hit and add +19 damage.) In other words, a single stab from a knife could leave a little cut or incapacitate you instantly.
Now imagine how unpredictable a fight becomes when you add in differences in size, armor, weapons, and -- most important -- attack and defense skill.
In these revised rules, two things determine your character's survivability: luck and skill. A bad die roll could result in your death. On the other hand, a highly skilled character could make mincemeat of a lesser skilled individual, even if the lesser is turtled up in the best armor.
Fights are unpredictable. They are not balanced. Even the best prepared character can end up slain from a peasant's stone, while the worst prepared just end up dead. That's the way I like it.