Because the vast majority of hunters will never shoot an animal further than 200 yds and BC doesn't play a factor there.
Exactly correct! Heck, even double that range, out to 400 yards, difference due to B.C. is almost non-existent, assuming you're using a bullet of some decent BC to begin with (ie: the 0.5-ish BC of a 180 grain .308 plastic tipped boattail) -- the difference in trajectory between say 0.66 BC and 0.50 (assuming a 3 inch max-height-above-sight-plane zero), is about 1.4 inches. Even if you had a true 1/4 MOA rifle, your group sizes under field conditions (heart rate up, adrenalin pumping, less than ideal rest position, etc) are probably bigger than that at 400 yards -- and honest 1/4 MOA "hunting guns" are (very) very few and far between.
Heck, even 500 yards (a rather dubious range to be flinging lead at any living thing other than enemy combatants) -- the diff between 0.5 and 0.66 B.C. is only about 3 inches. Get out your tape measure and look at it -- 3 inches ain't very far. The killzone on a moose is what, almost 2 feet? If your shot placement is so poor at 500 yards that 3 inches makes a big difference, you need to go back to sniper school.