If the archer is wearing protection, it should be modeled as damage reduction. I.E. armor. "Normal armor" is still armor and it should be statted appropriately if it's being implied.
Even in the image you've provided, the archers are actually wearing a form of light armor accessories, and could possibly be wearing gambesons. Which is light armor... which is an item... that you have to equip... that prevents you from equipping stuff for archery in the base rules.
Sorry to be a bit combative, but I genuinely fail to understand what point you're trying to make outside of being artsy and contrarian for the sake of it.