Kinda this is why I'm so against crit. It's not very helpful to a LOT of caster DPS. This could be fixed by switching to mastery or haste or just adding a third secondary stat to the final staff.
I'm against the hit (or at least so much hit) because we should be hitcapped or close to it before we even get into the raids where we farm the items to finish the chain. It doesn't make sense to have that ridiculous amount of hit on it; we'd have to have items in reserve to switch around so we're not crazy over the cap or we'd have to reforge out of a lot of the hit once we first get it.