I don't think there's anything that strange about Nintendo not saying anything. It's actually a fairly standard Nintendo strategy, if past history is any indication. Especially recent history. Yes, they have told us more about some of their other stuff (but only some; they barely told us anything about Donkey Kong, Kirby, or Other M). The 3DS is a console, not a game, so it doesn't exactly follow the same rules. It's also something they were clearly able to build up hype on, and use that to their advantage.
Twilight Princess was in a major way killed by its hype. It was a good game, but it wasn't the amazing redefining game that it was implied to be and that everyone thought it was, so I think Nintendo has learned not to generate so much hype with the Zelda series. Furthermore, the Zelda series is just generally massive, and they either want to keep it under wraps or, frankly, they just don't really need to spend the money on advertising to make people buy it. It's Zelda; people will buy it.