When MC says "completely new instrument," she means it, too. Reading hands-on reports about DJ Hero, the input is completely different from...well, anything I've ever done, video game or otherwise.
If you've ever done actual DJing with actual DJ record decks, it's a fair bit like that (ignoring the coloured buttons on the record part of the controller >_>). To be a truely authentic experience it needed two record turntables, and to remove the buttons, but instead it had this system of "this button is the left record, this button is the right record, and this button is the sampler" which nobody who's not a DJ will figure out on their own. Granted, two turntables would jack up the controller cost even more, so I understand why they didn't do it....
We've been getting alternative controllers since -Duck Hunt-, old man. >.>;;
You do realize there was a home console on the market with a light gun 13 years before Duck Hunt, right? (Also: 3 years before the home version of PONG, but that's a different story).
Which raises the question of where all the wiimote-as-lightgun games are...
They uhh...already exist. Hell, one of the games in Wii Play is effectively Duck Hunt 2 (it really plays like it too).