There are a few things that might have changed since that rule of thumb was invoked.
One, we've gotten taller as a people. Justin you're proof of that. By itself that wouldn't make any difference though, since theoretically we would still have the same geometry.
Two, we anchor farther forward than was popular back then. Corner of the mouth instead of the back of the ear. So as a percentage of our height, I think our draw length per unit height might be about the same as a short Englishman in the Middle Ages.
Three, we aren't going to die if our bow breaks. Being in a battle with a bow, I'd want a good safe design too.
Four, we have brought design along nicely from the ELBs and flatbows of old. Better woods, sometimes maybe better craftsmanship too. Not that there weren't great bows made back in the old days, but if you were arming an army I don't think you were taking as much time with each unit. Even Bear Archery has a certain rate of failure and thats with modern materials. Of course, they had simplicity of design and materials in their favor.
Just some thoughts. I certainly agree that a bow needn't be as tall as you.
