And I don't think Sakura's death would really develop Naruto in a positive way. Jiraya's death seemed to served that purpose and if someone else that close to Naruto were to die he would only feel grief. Whatever immaturity Naruto still shows is because of his young age, and not because he's a bad ninja or because he lacks some kind of serious shock. He's dealt with all kinds of hardship his whole life, I don't think it's fair to say that somehow Naruto is naive to the ways of the world, especially after his encounter with Nagato.
It's not so much that I think he's naive it's just that he seems to turn a blind eye to Sasuke's actions.