OP I don't think you have the right idea on some stuff. I don't see account-wide stuff as the issue with the loss of the MMORPG feel of WoW, but rather a lot of side things that felt fundamental to the feel of an MMORPG being eroded.
In particular, the latter few points as well as a general sense of agency, ability to make mistakes, complicated classes with synergies that you need to pay attention to, buffs to apply that aren't just flat stat increases that you fire and forget, talent trees that - whether an illusion or not - make your character feel personalized and give room to learn, stats that mean something beyond "this makes you hit faster, this makes you cast spells faster, this makes your attacks do more damage sometimes etc".
The game is just too stripped down, and nothing has been added in its place. The game doesn't have the kind of complicated, sometimes overwhelming but grand and exciting feeling of an MMORPG and the sense of progression we miss and the current developers are intent to keep it dead under some assumption that we want a streamlined action game.
Account-wide is fine. Having mounts and achievements on all our characters isn't totally killing some aspect of the game. But it's more like a symbolic change of a change in direction for the game itself that never seems to end with these current buffoons of developers.