I think you're forgetting that there are core gamers out there that also play musical instruments or have knowledge about music on a composer/playing level.
That's probably why guitar hero resonated with so many of them, because whilst it isn't a way to learn how to play a guitar or a real alternative to a guitar, it's fun and gets certain fundamentals correct.
Problem with Wii music is that it doesn't do that. From what I've read, certain instruments representations in-game are too simplistic so that they don't truly represent the instrument, and others are too complex that they also don't accurately portray the real thing (I've heard the drums are a bitch).
So I would not say it's too hard to play from the basis that it's so close to realism that core gamers who don't play instruments won't understand it, it's more like it's strays so far from realism in the fundamentals (i.e the instruments themselves) that it "sucks".
Personally, as a "core" gamer who doesn't play a musical instrument, I hate Wii music. Not because of what it is, but what it's creation implies. Miyamoto spent X amount of years working on this game when we could have had another Zelda or Mario by now.
EDIT: By the way, I think you're warning is laughable. Yes you do have the power to report people but:
Moderators decide who gets banned, so just because people disagree with you and do so harshly (you perhaps may deem them a "troll"), a Moderator may just take it for what it is, a harshly worded disagreement, and the poster would not have known about the reporting and nothing would have changed.
So you threatening to report people is pretty pointless, when we all have that power and the person "trolling" is also aware of that power, I doubt they fear banning, and because of that, I doubt your warning would concern them.
