they've probly tested the online and found the best way to even all the guns out so the higher rannk guns are only slightly better and not allot better, otherwise everyone will be running around with the same gun, or same 2 guns. like COD and the ak74 lol that was a stupid game
1. The best way to balance guns is to have them all even, not having some "slightly better" than others.
2. Every top tier weapon since CoD4 was always a low level unlock or you actually started with it.