Because he is the main character.
Cause he has uzumaki blood and as i said before minatos clan might be special since hes the only one who can use flying thunder god kunais so naruto is somehow a special jichu.
naruto get spoon fed to get healthy and strong
sasuke doesn't? :sy: they're both the main characters, they're obviously going to have more special power ups and what not duh. ANYWHO, but i guess he's all chakra mode because Kurama doesn't have all of his chakra or maybe it's because Kishi doesn't want to draw Nardo as a hairy fox. Or maybe it's cause their bond still isn't quite perfect.