I thought it’d be cool if for this game, you’d be able to unlock tons of little trinkets such as music, artwork and in-game statues of the characters. Smash Bros. did that and it was pretty fun content to have.
The music CDs could all be tracks from previous Street Fighter games, and you could set the music up however you wanted; you could set the rate at which the music appears, disable certain songs, set certain songs to play only when certain characters appear, and even have the same rules apply when you go online. So let’s say I never EVER wanted to hear Sagat’s SF4 theme, and only wanted to hear his SNES World Warriors theme. I could set it up that way if I wanted.
They could even have unreleased versions of certain tracks, like the theme that shows up in Hakan’s reveal trailer instead of his normal SSF4 music. That’d be pretty sweet.