I think the days of shovelware selling on the Wii is over. The Wii is on the downswing. The Wii-U was announced, the 3DS has Nintendo seemingly all in and the Wii gets the shit end of the stick. It's not doing poorly, it's just not selling at the virus-like rate it once was. I'm lazy so this will be quick and dirty.
There's a few ways to look at sales. First, they may be scared off by the content. This isn't an RPG console. Console JRPGs are almost non-existent and completely forgotten about, outside of Final Fantasy. Remember the days when Chrono Chross, Dragon Quest, Xenogears, Suikoden and games like that were major console games and people awaited them?
Poof. Fast forward to today, where if it isn't Final Fantasy, it's going onto a handheld, or is a Western RPG, like Fallout or Elder Scrolls. And those aren't on the Wii. That may be scaring them away.
Also we should take into account the fact that there's more to producing a North American version than just PAL-2-NTSC. The voice actors are British, and while that worked in Fable they may want to pay a whole new cast to redo the voices. That takes programming, time and money. And while we're on the concept of money, you have to market this thing. Most of us are gamers and believe that everyone thinks and acts like we do-reading forums and buying games without seeing one single commercial or banner. That's an easy way for a relatively new franchise to bomb and sell 120K out of the 250K Nintendo made, while the rest sit in the $15 and Under bin at Walmart. They need to advertise it. Now I do believe with the proper marketing campaign, it can sell over a million. There are people waiting for something to play on their Wii, and JRPG gamers still exist. Tons of them. Give them a reason to buy your machine, or turn it back on. Really pump the reviews it's been getting everywhere else, show the best parts of the game in TV commercials and get some Youtube ad space. The only negative to trying to market this game would be the name. It's made by some of the same people behind the other Xeno series, it has the same name, but it's different.....huh? That's not an easy sell but if anyone can do it, Nintendo can.
My guess is they don't want to spend for the marketing it'd take to sell it. Someone likely pulled up a powerpoint presentation detailing how JRPGs are dead and waggling, shooting and tablet gaming is in these days. Hence the blind eye and the Wii-U tablet thing. I'd guess they assume JRPGs are going to become even more extinct and are just trying to be ahead of the game, so why not release it somewhere else to test the waters?
I'm grasping at straws here. I understand business and marketing, hell I have pieces of paper from educational institutions saying I'm super duper at it, and I still think this is an oddball, WTF move by Nintendo.
But we shouldn't be shocked. Nintendo has always been a company who, for every couple genius decisions, makes one decision that forces you to believe they're completely senile and riddled with syphilis and schizophrenia.