Imagine if that scene was animated how everything else was. It wouldn't look like he was moving very much at all. At least in this it showed a really fluid movement.
I'm actually pretty sure that it was purposely done like that to add to the whole thing. Beside, the animation was actually quite smooth, it was the artwork which leads again towards the "purposefulness" of it.
Make any other animator do the fight, and it will be crappier than this version. The animation studio did their best to make this fight, the most epic one in the Naruto Anime hystory.(no sarcasm)