I'm going to posit this question here:
Given what we've seen said about Xeno and XenoX in the Iwata Asks, would it be a safe bet to assume that Nintendo is unsure of how to market a more core-oriented RPG like the Xenogames in Japan (and, in general, really). Most, if not all of their commercials, are always aiming to be charming, colorful, and lively, and I don't know if they know how to extract that from Xeno. I know they had adverts for the game, but they never gave it a commercial run.
Conversely, from the western point of view, where I think they are going to be pushing the title to Holiday seasons both for convenience of filling in Zelda and for higher returns on the title selling, I wouldn't be surprised if we saw something akin to the string of commercials that came with Hyrule Warriors or Bayo2 (though in the latter case it didn't help much). I think they know how to make commercials for the "action" crowd in the western demographics but have no idea how to handle it in Japan...
...That or they thought XenoX, a huge project for them, had no need for advertising outside of the Directs in Japan, but I find this suspect in general.