Why is that a good thing, though?
You can make that argument for basically any mount, skin, toy or pet, in any of the expansions we've had so far. And doing old content for them is something a lot of people like to do. It's something that keeps people playing, without actually having to do shit, but to keep old content and it's rewards, obtainable.
Or is this one of those "my precioussss!" things? Because fuck that.