Do y'all not realize who Murtagh as a character really is?
He was a broken man running on false confidence in the first four books. He was never properly trained aside from swordsmanship by Tornac. His dragon was abused and never allowed to properly grow mentally until they finally defeated Galbatorix. Of course Thorn struggles and doesn't seem as ferocious as a dragon should. Have you ever met a child of extreme abuse? They often are mentally stunted years behind what they should be. This is the struggle for Thorn. Murtagh grew up outcasted and despised but not of his own doing. This doesn't make him a "bad boy with daddy issues" character. It makes him a broken young man. He struggles to trust, never had a proper father figure besides Tornac (only for a few years before he gave his life for Murtagh), and has a great deal of trauma to work through. Of course he makes dumb decisions. Of course he struggles to get out of situations that are complex. He is literally in the phase of learning! What Eragon dealt with throughout the first two books of an extreme learning curve is what Murtagh in this story is dealing with, just against a much greater foe. Paolini wrote a terrific description of what it's like to be a man who's on his own with wounds to work through. I think many men will be able to understand, if not relate, to Murtagh throughout this entire story.