Yeah, but it's a bit odd to do that to the one character who's probably had more character development than any other.

I mean, I look at the alliance side, and there are exactly two characters that seem to have changed over the last two expansions: Mekkatorque, who finally realized that standing on a barrel and sending level 20 characters into a radioactive hole wasn't accomplishing anything and became the dynamic field commander his people needed, (not that it did any good) and Magni, who turned into a rock. (Though that may not count; frankly, he's affecting the story just as much as a statue as he did standing in his throne room for years.) Varian; Velen, Tyrande; they're all pretty much doing what they've been doing, and none of them seem to have changed much for it.

Horde side, there's been some development, but not a lot; most of the main lore figures are doing what they've always done: Vol'jin - "Me people are outcasts and I'm mad;" Sylvanas - "you know, Lich Queen has a nice ring to it;" Baine - "How can I fill my father's hoof prints;" Lorthemar - "Wait, what? Am I still in this game?"

If you think about it, there hasn't really been much character development among the main cast; the story's been advanced by getting rid of people and replacing them with different people.

So why take one of the most dynamic characters, and get rid of him? Personally, I think Blizz is better than that; whatever happens at the end of MoP, I'd bet it's not the last we hear of Garrosh. (And given how no one in WoW ever stays dead for more than a month anyway, that's probably a safe bet.)