Ubisoft's latest Rayman game is arriving on 3DS on June 7th (EU) now. That's why we haven't seen the demo or any screens or even a video yet.
I'd assume that the game was just not ready and they wanted to avoid some graphical errors (as with the Wii port) in this version, since the 3D conversion could be a bit more complex.
I'd assume that the game was just not ready and they wanted to avoid some graphical errors (as with the Wii port) in this version, since the 3D conversion could be a bit more complex.