So location can matter....
I really do not understand why they did not choice Therazane instead of Thrall. From a player perspective I can see how they would want to advance the players perspective but on term of just lore Therazane would have been a far better choice. Neth was the Earthwarden, Therazane is the earth Elemental Lord. Thrall would end up just kind of channeling her powers? Why not get her to cut out the middle man? Then the shamans could assist Therazane like they did with Thrall, though maybe they did not trust her? Only real reason I can think of not letting her do it.