I do empathize with Garrosh's position.
But at the end of the day he made all his decisions and pretty much all of them had nothing to do with Thrall. Garrosh even says he lacked guidance and was left to make his own choices... which he did. And he just said he would do it all again. Thrall only factors into the end of his story.
Garrosh isn't blaming Thrall for his life. I understand that Garrosh may hate Thrall, but to say in the same breath, "I would do it all again, fuck that coward Thrall." It clearly says to me he is continuing to blame Thrall for his issues; which is a problem because Garrosh has never blamed Thrall.
When Thrall accuses Garrosh of failing the Horde, Garrosh rightfully throws it back in his face, Thrall failed Garrosh. And Garrosh doesn't care because he thinks Thrall is a failure and a weak warchief/Orc.
What Garrosh would really say is "I did what I did and I would do it again, regrets and repentance are for the weak." If the writers wanted to slip in a jab while still maintaining a proper character, Garrosh would say "regrets and repentance are for weak warriors." calling back to the WoD fight cinematic.
Edit: lets put it this way: Garrosh is Thrall's whole story arc since Cata. Thrall is only part of Garrosh's arc at the end of WoD. The only time Thrall occurs to in Garrosh's story is when Thrall's story intersects. Otherwise Garrosh doesn't care.