Simple suggestion here. What if there were an enchantment for a bow that reduced the amount of time it would take to draw it back to full power? This would effectively increase the rate at which you could fire full-power shots.
Even if an enchantment isn't feasible, I think there should at least be a way to maniuplate this using commands, like a new attribute or something. Or maybe it could be tied to the Attack Speed attribute. I'm just throwing out ideas. Anyway, what's your opinion?