Ranged weapons always cause a bit of a headache to programmers, I think. That is why many games have used an overly simplistic approach when implementing these weapons.
Ideal system, you say? Very well, let me toss a few things into the hodge podge, and decide upon strengths and advantages of each point:
a) Projectile\'s path: When using ranged weapons, if a person is standing between the attacker and the target, said obstacle will be damaged.
The downside of this is the lag that inherently comes with Online gaming and the presence of many models and polygons on screen. Not to mention the stress caused to the server, who now needs to calculate paths between two objects to decide if the target is the one to be wounded or a third random object.
b) Distance: There would be a range of maximum efficiency for the weapon. The longer the distance, the slower the projectile\'s speed, the less the damage.
If the target stands too close, the arrow will not reach its maximum speed, the velocity of the impact between the arrowhead and the body will not be the highest attainable.
Downside of this? Complicated damage equations.
c) Fatal strikes: Self explanatory, a head shot, a perforated heart, etcetera, would incur in instant kill.
Downsides: Gameplay is affected by Counter-Strike masters that are capable of sniping with any projectile weapon. Also, if ranged weapons have this feature, melee weapons should possess it too (A fatal skull-cracking smash with a warhammer, or a slit throat with a dagger, or a stab in the heart...you call it). It has a consequence a very complex combat system with almost random chances of death (since as far as I know we don\'t control how our character swings the weapon)...very annoying.
d) Material fatigue: Bows are fragile instruments in comparison to melee weapons, which were designed to tolerate heavy blows. After a while, the stress caused by the constant firing of arrows would cause bows (particularly long bows) to snap in half. This is because the bow actually bends when charging up an arrow, the pressure is accumulated not in the tips, but the center of the bow.
Crossbows, with their moving parts and rather fragile gears, do not enjoy a long life either.
Downsides: Need to buy new weapons more often. Even so, it is realistic, and I find this idea rather nifty, if you ask me.
May think of more when rested.