I think its a couple of things:
It's January, console sales of current gen machines will be quite low at this point. Probably looking at 35k per week? (dunno but someone could find last Jan sales and figure that out).
Nintendo don't know how much stock to make, just like the Pro and other consoles before, they'll release more pre-order stock in batches, just cause its out of stock doesn't mean they won't add any more.
Lets not get all excited, personally I think it looked pretty boring, but as many have said before, lets wait for the dust to settle a little rather than jumping to predictions of success or fail.