"A NAME IS A CLOAK OF LETTERS THROWN UPON A MAN. IT MEANS NOTHING." - Transcendent One, Planescape: Torment.
Oh and tyrande was on her knee just fighting lesser doomguards and felhunters in the well of eternity istance, on the other hand illidan that was slayed by champions later in BT was tanking Mannoth like a boss. Or sylvanas and jaina having their asses handled to them by the Lk in hall of reflection, Sylvanas being killed by the ridicoulus boss of shadowfang keep, or Vol'jin being nearly oneshotted by the stupid rogue sended by Garrosh during dagger in the dark scenario.
And Garrosh is a douchebag... yeah, right? I'm suprised you put it that lightly. Yes, right now he is a terrible person. Somebody who probably will threaten the Azeroth for both sides of the conflict. He is a bad guy, let's face it, I don't like the fact they made him to be one, but he is. And, the thing is, he is much more interesting character than Anduin, Vol'Jin, recent portrayal of Thrall. Garrosh has a long and intriguing backstory. It's always somehow tragic if you look at it as a whole thing (although I doubt Blizzard does). He is a character who NEVER wanted to lead anything or anybody, who dreaded to think about it - and it was shoved into him by Thrall, the very person who released him from this burden in Nagrand.
You obviousy know much about the lore, but your hate towards Garrosh is pretty funny indeed. The only person I find really responsible for this clusterfuck we currently have is the one who thought "well, we have a newcomer orc with mental problems and who is repulsed by any idea of leadership. But he fights well... We have a new Warchief!". Garrosh is a wrong person at the wrong place.
And really, do you really think "douchebag=hate"? There are many examples of great video game villians who were also douchebags - most recently Vaas from Far Cry 3 - and they were the most interesting and memorable characters in their games.
One thing to take into account is how strong is our Character's, I believe lor'thremar was the First NPC ever to state that our characters were famous in Northrend and the events during the cataclsym stating ourselves as Legendary Heroes. Another question would be Who ended up killing said Expansion end bosses. Was it the 10/25 players who killed Lich king / deathwing. Or was it Tirion Fordring and Warthion/Dragon Aspects who killed there enemys.
We as characters have done insane Feats of strength, Killing old gods, slaying elemental lords in the home Realm (Al'akir and Ragnaros in heroic both permanetly dead)
I'll just give my two cents on the topic.
With regards to Garrosh; Capable warrior but realistically speaking anyone possessing magical prowess (warlocks, mages, priests, death knights, paladins), speaking of us the players, would probably have a very easy time killing him. As someone already mentioned, he is but a warrior and nothing more.
Now faction leaders and other notable persons are indeed fairly overdone to appear demigods, but once more we'll have to look at this a bit more realistically speaking.
We, the players, are also very powerful in our own right especially if we take this as players that are level 90. To be honest we would give most faction leaders quite a challenge, we might even be capable enough to kill them (except Velen I'd say).
As Christie Golden said Garrosh is not strong as he pretends to show. Garrosh is weak actually both in his core and in game. Any of the other characters and leaders can beat him and some of them without even breaking a sweat. Varian could have killed him 3 times by now. He lost his weapon 2 times to Varian already. He was saved by some deus ex machina outside force each time. Thrall according to the comic could easily have blasted him to oblivion anytime he wanted. Let's be honest he defeated Deathwing. Garrosh is nothing compared to him. Jaina? Pointless to say that Garrosh wouldn't last 1 second against her.
In general any of the characters or players can beat him. Garrosh is only power,power and power. No skill, no tactics, no experience and most important NO SPEED.
Garrosh isn't that strong from a Lore, or even gameplay point of view.
My feeling is to bring him up to standard, we may see something occur with the Sha, and we somehow bring the infestation back with us to the rest of Azeroth. I recall during BlizzCon, how a Q&A Panel answered how the expansion would start, and that it would look something like this:
Patch 5.0 - Small elite force (Us) invade the new continent to pave a way for the rest of our fleet.
Patch 5.1 - Remaining forces of your faction arrive, and begin their process of trying to dominante the new land.
Now both of these we've seen come true so far, but what is interesting is I recall them saying that we will eventually come back to Azeroth. Perhaps not in Patch 5.3, maybe even at the end of the expansion, but at some point we'll bring the Sha with us, and we'll end up infecting Garrosh in full, along with the decimation that has been caused by the Cataclysm, the rest of Azeroth is just a prime place for the Sha to infest!
Besides, even with Sha infused powers Garrosh is only on par with the likes of Illidan. The Lich King and Deathwing are out of his league completely.
So yeah, even with some sort of power boost it does feel kinda anti-climatic, doesn't it? Garrosh will most likely be the first end of expansion boss that isn't stronger than the previous (lore-wise)