Divine Protection (the pally CD) is their equivalent of Barkskin, so i wouldn't campare it to your tanking stance passive, which the pally equivalent would be sanctuary (+10% armour and -15% damage taken) paladins have the abilty to mitigate magic with their "active" rotational defences, and boost that source of damage reduction with stats, Druids don;t have that option so i doubt it;ll get nerfed.