Board Thread:Theories and Speculation/@comment-3568954-20150528121354/@comment-25349026-20150603004010

No, this is one of the dumbest things Kishimoto did. He undid the dramatic effect of Gai's final assault by allowing Naruto to magically reassemble his body which was literally disintegrating. Ok, so Gai lives big whoop, but if Naruto can rebuild his ENTIRE body, and grow a new eye for Kakashi, why couldn't he rebuild his own arm, Sasuke's, or make Gai's leg better too? Ok, so we'll say that its a limit to his power. So, Tsunade can magically make new arms for Naruto and Sasuke out of Hashirama's DNA which seems to be more easily found than a nymphomaniac's. But....she can't/won't make a new leg for one of the most powerful jounin at her disposal.

The problem as you can see is threefold, he could have died as we expected and would have had the most dramatic effect, or two people with super god healing powers could have fixed him better because its been shown that they have with other people.