For what I've read before, Nintendo wants to get the game out as soon as possible to get people interested in buying the Wii U and 3DS.
That and the fact that Project Sora (a miniature dev studio, like HAL Laboratories and Intelligent Systems, and the most recent project that the creator of Smash Bros) was shut down shortly after completing Kid Icarus might have something to do with it.
Of course, IIRC, Brawl had help from Game Arts so this isn't the first time the series has looked beyond Nintendo's own development studios and might even suggest that there won't be any Namdai representation herein.