Lets be real, Gjallarhorn was more than a weapon. It was cheese incarnate. Charlemagne brought up a great point that most bosses are bullet sponges and the community hated it. Gjallarhorn became (in most people's minds) the one and only way to get your loot fast and easy. Without having to design all year two bosses with scaled up health to survive that onslaught Bungie is paving the way to better boss fights.