It seems to be the normal thing now to wait for the last minute to release details for companies to release. I believe Microsoft announced the Xbox one six months before release. Sony took seven. I believe we will hear something next month before Halloween. Otherwise I would think they will delay the NX. (Like we need that!)
As for why they are doing this it is probably because they do not want others to start copying/countering their product. Remember Smartglass or the sixaxis and its motion control? Nintendo just doesn't want competitors to be prepared to fight the NX. The best way to fight is with the element of surprise.








