The mere fact that you are even comparing the graphics of FPS's and rock band is crazy. In an FPS, like Half-Life 2 or Bioshock for instance, entire interactive worlds are created. They have dynamic lighting effects that change how the objects and terrain in the game are viewed based on what angle you are viewing it at and what material you are viewing it through (glass, water, ect.). Also, particle effects and water effects are also present in FPS's. Another point is that other game genres, like FPS's, have things like the source engine which can create mock physical universes where objects will interact with eachother in real time based on newtonian physics. Games like rock band just have a list of stages and a list of character models with pre-set animations that are shown with pre-set camera angles. Comparing the graphical/ technical achievments of a game like rock band to half-life 2 or bioshock is a giant joke.
Also, I really enjoy music alot, hence why I play real musical instruments.