My take on why there was some lameness surrounding the use of rasen-shuriken on Kakuzu was simply because of the ho-hum animation this episode. I mean the Oodama-rasengan landed against Itachi was so much more lively in effect and satisfying, as unsophisticated it may be. But here, it's just Kakuzu getting prickles all around him + a generic sphere, without much particle/wave dynamic in between.