Ranged still gets a higher damage increase from headshots, right? You also have to factor in that most archers use bodkins, and all crossbows do pierce damage. My cleaver (36c) can hit people with godly plate armor 2-3 times in the head with no kill. It's harder to aim them, but spear and dagger thrusts to the head (you gotta jump and stab with the dagger!) usually take people out in one hit.
If your massive 2h sword didn't 1 hit someone an overhead, you probably just missed their head and hit the shoulders. Happens to ranged too. Nothing like seeing someone walk off an arrow to the jugular vein.