I think you're the one who missed the point. You wouldn't use Drill Cannon over RamsGlowercracker because the 5% from Brotherhood is less than the roughly 8% more damage that the 130 potencies provide. You'll also never use Water Cannon because Glower has enough range to be safe and of course that 10 more potency. OUTSIDE of the Carnival, there are only a few reasons to use different abilities. Rams Dragon for trash mobs, Petri-Cannon if your fighting things on a level of 5, but both of those go away when you're fighting bosses or immune mobs and you're stuck in a simplified monk-like state, where you burn your cooldowns and then spam one or two other abilities until your cooldowns come back.
