Board Thread:Naruto Discussions/@comment-26636534-20151016181609/@comment-1872728-20151023182400

Curse of Hatred wrote: In-universe reason: Because it works. Same for normal rasengan and shadow clone jutsu. Rasenshuriken just so happens to be one his most powerful attacks. Plus he feels comfortable using a jutsu he's been using for all these years. I would say it's this as well.