Some points to state before making a comment:
a)I've never played this game, nor am I interested in it.
b)I own a Wii (well technically my son does but I have access to it :P )
Now onto my POV:
I've read and understand both sides of the argument, but let's look at it from a different perspective:
Nintendo has had a history of producing shovelware (mario party comes to mind) and a history of making great games (Zelda, Metroid), and I can't happen but stop to think that while producing titles that many self described hard core gamers love, they can't all be gems.
As a company Nintendo needs to make money, so they look at something like Guitar hero/rock band and say : "hey we can cash in on this!" so, they go and make a music game where they basically can just slap something they already have developed (miis, motion control) and add music to it, 2.65 million sales later : $$$$$
All that $$$$$ can go a long way towards developing another gem, which will make the hard core gamers happy again. Or it could go towards refining the basic formula for Wii music 2 and make them all angry again.
In the end, you can't please all the people all the time, but remember this: Nobody is forcing you to buy the game.
