Because GG can net you 4 insta-kill body shots from sniper distances and relative safety. Blade Dancers got nerfed a little too hard. I don't think a single shotgun blast should be enough to counter a super. Now, a shotgun melee if you're quick enough and catch them off guard, that's different. If you're skilled enough to pop a heads hot on somebody with a sniper mid super, I think that should always kill.