Yeah, I know that some people may like the music out of a game more than the game itself. Would you buy the game or would you buy the soundtrack if you could?
Never bought a game just for the Music.
Having said that, I have purchased the sound track to games and some games have had some great music.
Some magazines used to giveaway CD's of game music and I picked up a few of those.
It's a nice thing to have, but it's not enough to warrant a purchase on its own. If I purely like the music (such as with Wario Master of Disguise or Mario Pinball Land), I simply download the soundtrack from somewhere online/listen to it on YouTube.
That said, a nice soundtrack does help sell the game, I'll say that much. It just can't be the only decent thing about it.
I buy games primarily to play them. If I like the soundtrack of a particular game, I would research the web to find a store that would purchase the soundtrack. Some soundtracks that I like are the CupHead soundtrack, the Mass Effect soundtrack and FF12 orchestral soundtrack.
The only time I think that happens with with a Guitar Hero game or something similar. Other than that, I've never listened to a games soundtrack before playing the game. For me it feels wrong. Like, if I want to play the game, I feel like I'd want to hear the song the first time with its proper atmosphere.
No, they want to listen to the music while making your self feel like you are the one who is playing the guitar. By the way my most favorite song in guitar here is of course the favorite of everyone, Sweet child' O mine. Specially the intro sometimes I close my eyes while I am doing it, (I memorized the buttons of course). It make you really feel like a rock star.