A big reason such big titles don't get translated are (that's only my opinion, though...) that they probably won't sell enough to turn a high enough profit. The game is quite expensive in Japan, so if they price it high in the US or Europe people complain about the high price. In Japan The Last Story's price is 6800 Yen, which translates to 82$ in the US. But many (not all!) US customers already complain when Wii games cost 60$. You just can't expect to get all the good stuff if you're not willing to pay good prices for it. (Sorry if that feels like a rant... it isn't.)
Translating a game with that much text into English and other languages (at least German, French, Spanish and Italian for Europe) costs a huge amount of money and it seems like Nintendo think that it isn't worth the hassle (yet).
Having said all that I still think Nintendo MUST translate that game and publish it in Europe and America. It's a tragedy if they don't. They made so much money this generation it would be nice to give the customers something back.