I don't agree at all. When he regains his true personality, we see that he becomes more open, more sincere and shows us he's way more goofy that he tried to look. There's a wonderful scene on the highwind with Yuffie in which he talks about how much he gets sick, just like her and is totally opposite of his usual stern look that Nomura likes him to portray him so much in AC. The actual Cloud is way more clumsy, goofy that his fake personality, something that the late game and even sometimes before, shows quite well.
What's more he totally places his trust on his friends to save the world, even if he considers it like his 'mission', he's glad he has his companions with him before entering the crater. Not only he becomes way more open about himself, even about his weaknesses, he learns to become dependant and perfectly understands he's not the perfect soldier he dreamed to become. He learns he needs others to succeed.
Then AC throws all that for the window, there's no sign of his actual personality in the movie, none of his more affective side, none of his more clumsy side, none of his more dependant side, he becomes his glorified super soldier image from the first half of the original game and never goes back. That's not a good character arc, that's shitting on everything that made your character relatable for the 'emo' image people built around him.