The ones who voice their opinions the most are absolutely clueless. I used to be the same when I was like 12. Couldn't care less about balance as long as the graphics/art style were fresh.

Making the BR (or any ranged precision weapon in Halo) a starter weapon would make almost every other weapon redundant, because most maps in Halo really don't give the AR/Plasma Rifle/Pistol/Shotgun/melee weapons much of an opportunity to outgun rifles or power weapons. Instead of making the player search the map for their own preferred weapon combo, it'll just become a BR duel fest, which makes for pretty monotonous gameplay imo. The trouble is giving the player weapons that give reasonable stopping power against campers off spawn, but not ones that they're just going to go out on the offensive with.