I don't thing like OP, when garrosh become warchief he was not ready to this job yet.
He was a great hero, and he wants to create a great horde, he has doubt about his father, and he's never known the truth about his father.
He belive his father was a true hero, but his father only fix his wrong choise, Thrall helps Grom to see what he had made, and in the fight against manorroth Grom hit as hard as he can, it was a fight or you kill or you will die, Grom doesn't espect to die in battle.
Grom drank the blood not because he was obligated but because he wants power, and Garrosh is doing exatcly what his father does.
In my opinion the noble hero was the Thrall's father, the Durotan forstwolf, who doesn't drank the blood and was killed by his choise.
Thrall has suffer so many thing since he was born, and those things made what he is, after theramore's fall Thrall made a choise to not back to be warchief, he made so much for horde, he creates the horde, after many years fighting, he wants to do something for himself, to be a shaman (he believes he can do more being a shaman than being a warchief).
I think another hero needs to born and make the right decision.
A leader is not something you can choose, it is the natural path, maybe it was the thrall's fault.
I would like to see Jaina and Thrall being a friend again, they used to be a good friend, and Garrosh kills this friendship.