Back in the days of MoP:
Remember the legendary healer cloak? It's effect was pretty useless for disc, because your heals almost exclusively were smart heals and the majority of your throughput (absorbs) were not affected. In the end most disc priests went with the damage cloak.
Now in WoD:
Again a huge build up until you can finally get your legendary ring. But then, Déjà-vu, it's effect works fine for all other healers, but has only minimal effect for Disc Priests.
Why does the legendary ring suck for Disc Priests?
-The increased healing/absorb of the empowerment doesn't work with Atonement. But since even Archangel doesn't work with Atonement, this isn't really surprising. RiP Atonement.
-The absorb proc of the legendary ring at the end of the empowerment only counts effective healing and completely ignores all of your absorbs, which is basically all of the "healing" you do, if you know how to play disc.
-Negative interaction with other healers: All damage absorbed during the empowerment prevents other healers from doing effective healing and ulitmately lowers the amount absorbed from the legendary ring's effect after the empowerment ends.
-Disc has no raid cooldowns to push out massive amounts of effective healing, like all other healers do.
-Disc ability to do big amounts of effective healing (aside from penance every 9 sec) is pretty limited in general. Most of the time those "nasty absorbs" get in the way.
What does work with the legendary ring?
-The ring has a 2 min cooldown, same as Power Infusion. But compared to the raid cooldowns that other healers can utilise, this is only a minor perk.
-You can double dip from the empowerment with your normal healing spells. E.g.: If you crit with a healing spell while empowered, the healing will be boosted by XX%, and the absorb by another XX%. But, let's be realistic, you will only utilise this "bug(?)" once if you have Empowered Archangel up and go back to shield spam after that. Probably Blizz will fix it, just to mock disc priests some more.
I know, there are a bunch of people that might say: "You deserve this, that's what you get for stealing our effective healing, I hate disc priests!!111", or something of the sort. But you have to admit, that it's pretty depressing if you can only get a fraction out of the legendary item compared to other healers, just because you play another spec. You had to do the same quests, but you basically didn't get the same reward. Should Disc Priests afk during the empowerent, so your other healers can do more effective healing with their big raid cooldowns, so no absorbs mess with the absorb proc of the ring? Where is the logic in that? I could go on and on about items, talents and spells (e.g. lifeleech, twist of faith) that don't interact with absorbs, but this is probably the first time you can get a disadvantge if you use your absorbs. Didn't they test all this stuff, or do they simply not care? Even the damage dealer ring isn't an option this time, because atonement is dead, your damage is lower than in Mists and you can't activate the ring as a healer.
Possible fix:
Make Disc Priest (and perhaps Paladin) happy and let aborbs count towards the effective healing. It's that simple and a logical solution. The other healers still have their big raid cooldowns that they can use with the ring, anyway.