Edit: I don't think people realize how big of an effect this has. With BoA this means that if you didn't find this item before 2.1 then you will never be able to acquire this item. Which means that no matter what you do, a player that already found this item will always be able to cast one more smokescreen or vault than you will. In an environment where even a second matters this change is HUGE.
Where are all you BoA enthusiasts now? The whole BoA thing is about finding your own items. Or at least hoping that one day you will find it. Now, you cannot find it. If you didn't have one before 2.1 then you're already lacking a % of resource.
For DH this % of resource is huge. 8-10 discipline. Which translates to either 1 smokescreen or 2 vaults.