Nintendo has been doing directs clearly aimed at the upcoming seasons for years now. The only instance I can recall at the moment where they got really really chummy was in the first direct of 2013 where they gave us announcements for games that we wouldn't get in years, like Xenoblade X and #FE. And that's because at that point they REALLY had to give us faith for the Wii U given its rocky release.
In all other cases since directs focus on what their priorities are at that moment. Unless it's E3 in which case they actually go all out and give us stuff for a much more distant release window.
The only difference these days is that they figured they'd share info about NX way earlier to make sure people didn't think they were just going mobile, but instead it seems everyone, media included, started on this crusade to bury the Wii U and hallmark the NX as having to happen NOW or else. And honestly, it gets a bit tiring.
Why not show that stuff now? Because it won't do shit for anyone. E3 is the normal venue to inform consumers and investors of what's in store for the upcoming fiscal year. This thing we just got is just a minor as fuck direct aimed at communicating information on spring titles, DLC and the like… pretty much it was just marketing, it wasn't there to restore the faith of humankind and bring joy to the world. I don't even see why they have to keep convincing people that they're still thinking of the Wii U and the 3DS... they talked about both for nearly 45 minutes and people want MORE evidence of them caring about these devices. Seriously?
Not only that, but they did make it clear there's Wii U AND 3DS stuff slated for the winter. It's not stuff WE care about, sure, but it's there. Zelda they're probably not going to touch as a topic until they know for sure when it's ready given how many times now they've had to go back on their word on its release.
Lack of evidence is not evidence, and when it comes to things like these getting information means a heck of a lot more than not getting it. Particularly when considering it's a company like Nintendo that's rather touchy (and recently rather ineffective) on how they communicate information. You can build castles and entire realities out of what people have "speculated" about Nintendo.