Uh. I haven't really done a lot of CoEN simply because I haven't gotten keys for it, but that logic is pretty absurd.
The whole point of M+ and keystone levels is for them to have general parity in their difficulty. Is it going to be exact? No. To claim however that one should be way harder than the rest of them when they drop the exact same type of loot is completely backwards in design and makes no sense.
One of the dungeons has to be the hardest, and that's fine. It's absolutely fine design if CoEN hit that check box. It however shouldn't be so much harder than the other dungeons that it's really not worth doing. From an overall efficiency standpoint, I would just stay away from it if that was the case, and that my friend, is terrible design. Same problem existed with MoS pre-7.2, where people just did MoS because it was the most efficient source of AP (at least until people stopped caring about AP).
I don't think you understand scaling or difficulty very much if you think ToS gear is going to fix it. That difficulty problem is still going to exist lol. Yeah you're going to get more gear which will make the earlier levels of that CoEN easier. But I ask, why do CoEN if you could do way higher of other keys with that new ToS gear? That's right, you won't, which is why they changed it.
I'm all for difficulty, but having something arbitrarily that much more difficult "just because" makes absolutely no sense in the fucking system they ended up designing, it's just downright retarded. I say that as somebody who has done CoEN like twice (base mythic and like a +7 or something, which wasn't too difficult for me, but it still felt way harder than any of the old dungeons at much higher level). I did however watch my guild mates do a 15 prior to the changes and beat it like an hour after the timer expired. I ask, why would they waste time in the future if the difficulty stayed the same, when they routinely +2-3 most of the other dungeons?