In every expansion (or even content patch) there's been one roadblock boss that made EH king.
Every time Blizzard said they'd make bosses hit less hard, those bosses ended up hitting just as hard or crazy fast, if not harder.
Every time you want to progress, ie you're in less the optimal or BiS gear, you're going to want the safety of EH.
I remember the days of vanilla when healers would take turns wanding to take back mana. Yes avoidance was something you watched on your gear but you still went after EH. (Back in those days i didnt even know the term Effective Health, but i still pursued those stats out of instinct).
Thinking back to TBC where i actually kept an up-to-date avoidance set, i still wouldnt wear those. The only boss i remember that i actually would 100% don the avoidance gear was the dragonhawk boss in ZA. Thinking back now, i would probably choose a higher healthpool and more active use of cooldowns than go the avoidance road again. Blizzard will be hard pressed to come up with a scenario where i'd take corpsetongue coin over an hp trinket.