Back in the days of Wrath of the Lich King, World of Warcraft had 14 million subscribers. Then, some developer/designers came up with the idea of making the game "more interesting" by fundamentally destroying the premier healing abilities of the main healing classes. They also hamstrung the tanking classes as well. In addition, most of the new Cataclysm content was loaded with RNG mechanics that required just plain luck to get through. Sure, the Cataclysm expansion generated interest, and revenue, for a time. Then the absurd difficulty of trying to do dungeon and raid content with weak healers and weak tanks began to hit home.
The great exodus from World of Warcraft then began. Over time, they went from being 14 million subscribers strong - down to 7 million subscribers. That number is still falling, and can only now be estimated (some think 4 million is a good guess) as subscriber numbers are no longer being reported. That's billions of dollars in revenue per year. Lost for no good reason. And no, it was not just standard MMO attrition; the game just got plain bad.
With the latest proposed changes to ESO, I think ZOS should prepare themselves for exactly the same sort of fall to begin a few months after the release of the Morrowind "expansion". As it is now, casual players avoid the vCOS, vWGT, vICP as much as possible. I suspect with the destruction of the healing class, the number of folks willing to run that (and other non-classic content) will plummet. Yes, I know that the Elite players will have no problems, but they comprise only a few percent of the population (ask Deltia).
I think what ZOS has failed to grasp, and that Blizzard certainly failed to grasp, is that players LIKE to feel powerful! Players LIKE to feel that they make a difference! Players LIKE to feel that the class and role that they have chosen is the best that there is! If everyone has exactly the same capability to heal, the exact same capability to tank, the exact same capability to DPS? Well, then NO ONE feels that they are special in any way. And, most folks certainly do NOT like that!
So, ZOS, take it for whatever it is worth. It is, after all, just my 2c tossed into the pond.