As for your argument that Thrall is to blame. I think you and Blizzard think alike. I've heard Metzen say the same thing at Blizzcon before Cataclysm. Garrosh' storyline only served to deepen Thrall's storyline. Yes, Thrall is to blame for anything that goes wrong. Garrosh is too young and inexperienced to be good at everything, it was already expected that he would make mistakes.
To go about and say Garrosh should die is stupid. With this logic, the majority of people who visit these forums would kill children who make mistakes as well. Or what about political leaders around the world who don't always make the right decision, would you want them dead as well? It's so stupid.
Garrosh deserves more than to be killed in the last raid. He deserves to be on par with Saurfang in awesomeness. Maybe he isn't Warchief material, but he's surely a good warrior and he should lead the Warsong and be Overlord. In the pre-Cataclysm event that's exactly what he wished for instead of becoming Warchief, so yes, it is Thrall's fault. Let's blame Thrall instead of Garrosh. And trust me, I still like Thrall overall. I'm not a hater.