Well. The Nintendo DS is really simple hardware to program for and lots of other shit like that. I mean, hey! The Amiga demo scene still exists and is alive. LOADS of people bought a Nintendo DS when it first came out. Up to this year. I pretty much think that the Nintendo DS is the Amiga of our generation. Legendary system. Excellent games and us, the hackers might target it. A small group going by "fuk team" has already started. I myself has been wanting to be a part of the scene for a while. (Shoyru, better get some coding tutorials to be learnt!) If the NDS has had marketing levels like the last couple of years and now. We probably could start a whole new array of groups and individuals that create awesome games for the DS and end up with competitions, parties and everything! The scene could be extraordinary for all I know. I'll be doing homebrew once i have a better experience with C/C++
Simple hardware to program for? You need to get a flash cart and such in order to do it at all, and there's no official tools so you're relying on third-party support. If you're doing this on a DSi or 3DS, then a single firmware update could render your flash cart (and thus your work) unbootable because you're skirting around Nintendo's protections.
Compare that to other development hardware like arduino, which is cheaper, has official support, and lets you explore hardware programming a lot closer (assuming that was your focus).
For a higher-level focus on features, though, android devices still win. Much better specs,
cameras you can actually program with, and more. Even on the DSi and 3DS, flash carts still operate at the DS-level (outside of the iEvo which only halfway works).
As for DS demos and such...
http://pouet.net/prodlist.php?platform[]=Nintendo+DS&order=&x=32&y=7&page=1&order=
The DS has been out for almost 8 years, and that's all that's listed there.
So I don't think there's nearly as much enthusiasm as you think.