Hitpoints have always been a curious invention by gaming. I guess the frailty of our bodies is not very fun, and so to make gaming fun, we need to invent hitpoints.
Can you imagine if games were like real life in terms of total damage a body can sustain? You wouldn’t get three feet in a shooter game. The first bullet you took would shatter and shred your internal organs, leading you to bleed out all over the floor while going into shock. Not exactly stuff that would make a game like Gears of War a hit.
Huge battles in RTS games would be over in a few seconds. All your expensive units would die after being hit once, it would suck, but then so does war in real life.
One game that I must point out that does this differently is the S.T.A.L.K.E.R. series. In the game you are not a human tank. Bullets will deplete your health much faster, and even after you’ve been hit you will bleed, depleting your health further. While the damage is “more” realistic, it isn’t perfect. A bullet to the stomach would pretty much put you out of action. Still, the game is commendable for going the extra mile.
(Here is a really good and funny video review of it by Zero Punctuation)
What I find really interesting in games is how some weapons do more damage than others. Sure, if you want to talk physics a bullet has more joules behind it than an arrow, but both will still kill you. The total energy is different, but the end result is the same.
Perhaps the idea that some weapons are “superior” to others in games stems from the existence of hitpoints instead of the fact that weapons evolved for efficiency reasons and not because newer ones “killed you more”.