If Blizzard had the foresight to balance them properly. I actually like the new Legendary system. Mainly because it incentivizes you to get out of your class hall and play the game. That invisible carrot is the only thing that makes me still do my Emissary Quest. I can often convince friends to help me in a dungeon or raid they don't need just because there is a chance at getting a Legendary. I personally hated the WoD and MoP system of a Legendary that your guaranteed to get, that everyone else has.
It's amazing to me though how Blizzard thought they could add something like Prydaz, Xavaric's Magnum Opus onto the loot table though and not get crap for it. I mean that Legendary might possibly be why my more casual friends don't even log on anymore. They are trying to push harder content, but need to do more damage to do so. It took them quite sometime to get their first Legendary and when they finally get it BOTH of my friends got the neck. Hell it was my first Legendary as well, even for a tank/healer it's pure troll. I mean some of these Legendaries are just pure troll, while some of them such as the Arms Warrior Gloves or UH DK wrist should have just been incorporated into the spec to begin with.
Now as a tank or healer you don't really care as much about Legendaries. I personally play Prot and Arms on my Warrior but always have my specialization as Arms (despite tanking far more). I mean I'd love the Prot Warrior Legendary gloves for extra DPS or Ring for more Survability, but all of them on the Prot Warrior table are decent, they simply let me tank better. Same goes for my healer, some are far better, but I don't feel pressured to get the BiS one. But DPS is a numbers game, pure and simple, with a few exceptions. I don't mind that some Legendaries boost your single target while others boost your AoE, that's fine, but then other Legendaries boost my survivability....like eh? That's what healers are for.
And seriously....delete the damn neck. At least their buffing the ring so that it's super strong in Mythic +