Nintendo's Switch NDA restrictions.

[JEMC]

It could be because of many reasons.

One reason is that some of those games are already available on PS4/X1/PC and, with the holiday season right in front of us, most publishers may prefer to focus on those versions for now instead of announcing a version that won't net them any sales for another quarter or two.

There's also the fact that when games are announced, they usually come with some screenshots or a trailer. Using those things we could get an idea of the Switch graphical capabilities and that's something Nintendo probably doesn't want to happen before their big Switch reveal. Third parties may hold their announceemnts until they can actually show their products.

And another reason can be that Nintendo has already confirmed them that they'll show their games on the Jan 12 event. Revealing their games during that event can create more surprise and hype than doing it by themselves which, paried with the above reasons, makes them belive it's a good idea to wait.

Of course there's also the chance that there aren't many announcements because there aren't many non-Nintendo games being developed, with third parties just waiting to see how the machine does in sales before starting to develop for it. But honestly, who wants to believe this?