Proccing Ice Barrage via the passive Power Word: Hail within Frost Claw skill tree ignores the cooldown of Ice Barrage, thus consuming a lot of extra mana for no benefit as you can’t have multiple Ice Barrages active at the same time. At worst it might even interefere with the speed buildup since the previous one is overriden, but that’s difficult to test.
Not completely sure if this interaction is intended this way but I heavily doubt that otherwise it might have been specified. Aside from that, it doesn’t really make a lot of sense to override the buff.