Many reasons, ranging from the publisher being tiny and having never really done much on Nintendo platforms before to the gameplay being difficult to get across in trailers.
But I suspect by far the biggest reason is that it just doesn't look very good. I always see praise for the Wii version, but watching that trailer in the OP, I don't think it looks any better than the bland-looking WiiU/3DS versions.
And I don't think there's the same niche built in to Nintendo consoles that buy these look-bad-but-maybe-you-can-have-a-bit-of-fun-with-them small Japanese games that you get on PS consoles.
http://store.nisamerica.com/rodea-the-sky-soldier
The LE seems to be selling out okay on their store though. 11-25% left, which isn't a disaster.







