And besides, Beatmania already had controllers with keys (albeit only 7) in addition to the turntable, and that game was released in 1997.

Wait... fullsize keys... actual notes on a scale? (Unmentioned in the video) Actual MIDI keyboard? Awesome! I hope this is a trend towards being able to actually learn how to play songs on real instruments from these games.

Too bad the rhythm game genre has been in a slump after re-hashed shit from Guitar Hero and the awful Beatmania wannabe DJ Hero burning out the market.

Why assume that all talented kids are forced to practice?

If you really like something and want to get good at it nobody has to impose it on you.

And while you say this is more "worthwhile" than DDR, this game (and the sort like: Beatmania, DJMAX, O2Jam, etc) exercises your rythm, coordination, reflexes, concentration and flexibility similar to piano, and kids aren't forced to play them (quite the opposite sometimes) because they are fun!

http://en.wikipedia.org/wiki/Beatmania