Quote Originally Posted by AssertnFailure
Rasengans? Kakashi explained already that he could barely create something that could pass as a rasengan. His lightning affinity doesn't compliment that type of jutsu.

He didn't say that exactly. He said he can't place his affinity in it. So there is no use in useing rasengan when he already has chidori. Remember they are about the same power (rasengan chidori) so there really is no reason to use it. Rasengan is just an incomplete jutsu which it looks like naruto is the only one able to complete it in the end.