The thing about RPGs in Nintendo consoles is that, like Ian said, Nintendo doesn't make RPGs. If Nintendo made at least one game of every genre, and promoted it as the next big thing, I bet they could see money rolling. Wii Sports did this, it inspired (much for our demise) a lot of similar games (that suck, but hey).
Say if Nintendo made a serious fighting game, like what Killer Instinct was, and it sold 1 million copies, 3rd party companies that make fighters would take notice and would release their games. The same with every other game genre. I believe that The Las Story is this game for Nintendo. They need to market it and be 100% behind it, just like they did with Tales of Symphonia, the thing is that for the Wii, it's too little too late. RPG maker's won't flood us with RPGs even if The Last Story sold 2 million copies simply because we seem to be at the end of the consoles cycle.
This is why X-Box and PS3 have the FPS and the RPGs. Microsoft/Sony don't make those types of games (generally speaking, I don't own either and I'm not aware of ALL of their games) so they get a 3rd party to make a game for them, and then they put the $ behind it to market it and NOT make it fail. What happens usually? The game is a hit, even if it sucks, and the rest of the 3rd parties go "Oh, that game sold well there, we should put ours in that console too."
Square-Enix in my opinion won't marry to one console anymore, ever. The old excuse of "whomever has the best graphics wins" was just that, an excuse. They are pretty much an independent studio and do not need Microsoft/Sony/Nintendo's money to survive, but if they are paying them to put a game on their system, they will do it.
Nintendo needs to support these type of games that are exclusive in any way possible. They usually don't because they don't want to be related to crappy games, but all they need to do is try the game themselves. If it's a good game, exclusive and by a 3rd party, they need to use the full force of their marketing to make it sell, just like Sony and Microsoft do.