I think there's a market in both the second and third categories. What I'm saying is that at this price point they need to put interoperability first and not expend any resources on audio playback, where they will be inevitably reinventing the wheel to no good purpose. It's a bit expensive for a toy - for not much more you could get a decent pad controller like http://www.wirerealm.com/reviews/alesis-samplepad-pro-percus...

The advantages here is that you can build a complex virtual kit plus it's totally lightweight. A lot of musicians are interested in using and abusing gestural control for a variety of reasons, from convenience to spectacle, so I do think there's a market - but the musicians most likely to be interested are the least likely to want static sample playback or need another bunch of drum samples. I don't think low-latency output is impossible given the high frame rates the Playstation Eye is able to deliver, I'm just saying they need to concentrate their efforts on the advanced features.