Its big value is in events where a predictable emergency situation will arise, where you know a lot of spam healing will both be neccessary, and draw
really unwanted attention. In particular I'm thinking of a stage in the Queen Sendaii the Hive Queen fight, for those that are familiar. There are similar, if less dramatic, other examples from earlier content.
As a true crisis AA, as opposed to a tactical one, it can be good when you're running "without a net" as some other shaman put it. If the group you're with gets multiple uncontrolled adds (I assume shaman wasting aa on this are already experienced and advanced enough to have controlled some), and people with non-ideal agro abilities are tanking, then this AA would keep you free to take action as neccessary to pull out the win, instead of having to heal yourself.
I see this AA as a novelty power, mostly useful on raids. A fine thing to be spending AA on 'round about the 1k AA mark
