I like the idea of attunement, but something similar to UBRS, with a bit of an exception. Items drop in normal and above, and will be there everything. That means if you're in a PUG, you can get it. I like the idea of having to build something, like the Onyxia cloak or the seal of ascension. Having 5-6 different pieces you need and they drop from different dungeons.
There will only be a "grind" should you decide to get way higher level of the cloak than allowed for a given week by the soft cap of sorts, at least that's my understanding. It's the same as with islands. Some people keep crying that you are forced to do islands...and yes, that is true, you are forced to do 3 per week. Other than that it's just your min-maxing that you are free to pursue, but you don't have to.
So the cloak is basically nothing more as a buff that increases with time, making the raid easier as weeks and months go by. This is pretty much the same thing we've seen in many raids in the past. You don't even need to go too far into the past, in Uldir we had these titan stacks or whatever it was. Each week you got more, essentially providing a steadily growing raid nerf.
And I think it's way cooler to have a special item that you upgrade, than just having a buff that increases every week, like in ICC for example.
Attunements can go die in a fire... or, the people longing for them always have Classic.
What they did right, was the Suramar lead-up in story content and world building. Also, account-wide is a must. Give more of that, by all means.