I have a few things to say about this.
Like I said before, Bloodlust is a class-defining ability. It is one of the very few abilities of the Shaman that are currently still unique. In fact, almost all of our totems are overwritten by other skills from other classes; in some cases, this causes Bloodlust to be the only unique thing we bring to a raid! Because of this fact, I'm certain that if Blizzard continues with giving their unique abilities to other classes, they will become an obsolete class. And I don't want to have to reroll to a class I don't like, just so I can actually play the game!
Let me give an example. If a raid group were to pick an evenly geared Shaman or Mage for a raid, who would they pick? Naturally, they would pick the Mage; Not only do they have their unique raid-wide buff, they also deal more damage then Shamans with equal gear level! As for PvP, the same applies - Shamans have very few ways of getting away, while Mages have many. Now, let's include the Hunter on this list: While I believe that they have about the same damage output as Shamans in equal gear, in PvP they have a lot more survivability due to their talents and playstyle, which still makes them preferred over a Shaman in that aspect!