In my opinion, Wii Music showed great potential, and a sequel, done right, would be a potentially huge system-seller for the Wii U, akin to Wii Fit for the Wii (although they'd have to avoid using the "Wii Music" name in the sequel, as the first one stained the name too much). In my view, it showed a hint of where music games should be heading, something a little more than mere rhythm gaming.
Probably less popular than most opinions you'll see in this thread, but there it is.







