Think of it like gaming and smartphones.
Yeah, there are apps for that, and there are games apps, but there's a market for a dedicated device that has more capabilities. I have little doubt that the proposed technology is more advanced and capable than simple apps on phones that register your snoring.
That's exactly what I'm saying though. Nintendo's primary market in universally appealing, family friendly consoles and dedicated gaming handhelds has been tanked by smart devices, because people will rather have those kind of experiences on a platform they already own even if it's not quite as good because it's more convenient and cheaper.
The same thing has happened to cameras, sat navs, pc's etc.
And Nintendo's reacting is to try and get those exact same people who are rejecting dedicated hardware to use dedicated hardware for a task they can already do on their smart devices, often for free.
Again, I already have an app that I'm already using that does this, and it works really well. It might not be as detailed and accurate as a dedicated device, but for a good idea of how I'm sleeping it does the job. I cannot imagine why I'd want to spend money on something that would just do the same thing a bit better, anymore than I could buying a pager, or a sat nav, or a PC for web browsing,