Decent BUIS for less money?

[Frontier Gear]

If one has good enough eyes to be able to accurately engage targets using the BUIS does it not beg the question why not just carry an A-2 to begin with and forego the optics all together? One can shoot MOA with Iron sights.

Light gathering. For hunting it makes a big difference. I hunted with open sights for a few years until I realized that I could safety and legally take deer with a scope at dusk when I couldn't with open sights. It seems that deer like to come out right when antlers are hard to see without optics. An extra 15 minutes often makes the difference between meat or no meat in the freezer.