Technically you could still have multiple Shaman drop ToW even though they don't stack for the very reason you just mentioned, range. Let's just use a ten man for example. Group 1 and Group 2 both have a Shaman. Could you still use two ToW to cover a larger radius even if they don't stack? You still could overlap them to insure that the entire group can stay within range of a ToW right? So that being said it is not a complete nerf. Sure you can't stack them, but multiple shaman across the raid would help secure that regardless of location you would still be covered by ToW.