Well this wouldn't seem bad if it applied to sleep, root, tree, silence and fear as well(not slow however). That would actually address one my complaints how the pvp felt like just ganking and give every class a fighting chance against all classes(on first thought anyway). But I suppose the main complaint here has been by players getting ganked specifically by sins, rangers and killed while stunlocked. Something, seems to me, they were designed to do.
And this does affect sins more than others, only CC they have is stuns. Ranger has root, slow, sleep and the benefit of ranged attacks. Chanters depend on stuns too, fair enough but they have heals and buffs. Also as I understand most of chanters attacks are doable while moving?. Not the case for sins who also have positional attacks.