I'm with Rhoq on this one. Basically, the negatives just out way the positives and as Strell said its just not feasible. Though I'd love to be able to play my DS games on a tv and with more comfortable controls than the DS offers. I'm not knocking the DS, but I've never been able to comfortably play a handheld, but thats a different rant for a different day.
On the other hand, with the way Nintendo has been peripheral crazy, whats to stop them from releasing a device that is essentially a large touch pad but also wirelessly transmits DS game data to your wii to display on your television? It could be a small tablet with a dock for the wiimote to connect to, maybe allow its facebuttons to be usable on the tablet, but a pass-thru port to connect a nunchuck to...
Imagine a small tablet on your lap where you use your fingers instead of a stylus to do everything you would via the touch screen on a DS but have a small cursor representing your finger position on screen. The nunchuck can be used for movement, obviously, as well as add some extra buttons to the device. For instance, I've been playing Star Fox Comman recently and I really dislike the touchscreen controls for that game. I use a 'Comfort Stylus' to wrap around my thumb in such a way that it feels like i'm using an anolog stick but even thats only slightly less awkward than using a regular stylus. With this touch tablet, I can use my thumbs to control the game more naturally, and the nunchucks trigger buttons would be MUCH more comfortable than using the L button (or d-pad) on my DS. With a device like this, you'd get the tactile feeling of the touch screen with the convenience of sitting in front of a big ass tv.
Dammit, now i wish they had this in the pipeline.