Shamus (of DM of the Rings fame) loves the logistical aspects of the classic real-time strategy game Starcraft, but he hates micro-managing the tactical aspects of the game — which need micro-managing, because the characters are “too stupid to fight in a sensible manner”.
In fact though, the characters aren’t stupid; it’s the underlying combat model — 
which goes way, way back, to paper-and-pencil D&D — that’s stupid. Witness the trouble with hit points:
During this noble endeavor, we have a couple of lines of marines who encounter one another. Assuming both groups are arranged in an optimal manner (a line facing the enemy) and each unit fires at his closest foe (the one directly across from him, which is what the AI will do by default) then the battle will go to whoever happens to shoot first. If units employed one-shot kill weapons then all battles would be more or less a coin flip.
So, if equal forces face each other with one-shot kill weapons, it’s a coin flip. So far, so good. 
But what happens if characters have ablative hit points and take, say, eight cumulative shots to kill:
But I can direct all my righteous Blue warriors to gang up on one particular member of the vile and hated Red Team. At the end of the first volley one loathsome member of the Red Team is dead (hooray for justice!) and each of my guys has taken one hit, bringing them down to seven hit points. [...] Instead of Blue defeated and Red near death, Red is exterminated like the vermin they are, and Blue is in respectable fighting shape. It’s obvious that micro-managing doesn’t just give you an edge, it completely transforms the outcome of the battle.
The reason this kind of micro-management pays off is not that we moved to hardier warriors; it’s that we moved to a combat model that reflects that hardiness the wrong way.
What happens when we give each shot a one-in-eight chance of taking out a marine? We’re right back to the sensible results of the original one shot, one kill scenario — a coin flip — even though it’s more like eight shots, one kill.
This has another benefit that’s more pronounced in a roleplaying game with fewer, but more important, characters: a character might die from the first attack, or he might survive a dozen attacks. This is much more in line with what we know of wounds from modern guns and not-so-modern swords. No one’s immune to one single gunshot or stab wound, but guaranteed to die to the eighth.