I am so addicted to Rock Band and Guitar Hero so I obviously don't think they're lame!  I think of how my friends and I grew up on Mtv (back when they actually played music videos) and doing air bands. I can't think of anyone from my generation that didn't air guitar on a tennis racket so I guess that's why it's so popular.  Everyone wants to be a guitar hero.

That said, I think keyboard hero would be pretty cool too but would maybe appeal to a different demographic.  I think it would be cool if it was popular classical piano and Billy Joel and stuff like that.