Well it honestly boils down to, as
@Stingy Perry said, server cost and the additional space for the soundtracks, Those are all Out of pocket for Spike....
Then you have copyright issues. Yes, I know that sounds silly to worry about considering what's in the repo, but the music lawyers are almost if not as bad as the Big N Ninja lawyers.
It would, as I think
@Waffles said once, put another target on the site's back.
Don't get me wrong. I would love quick access to a lot of game soundtracks, and the old 8 and 16-bit ones probably wouldn't take up much space.... It's when you get into the PS1, Saturn and on era that it’s full CDs, and fully ripped HQ CD soundtracks can be rather large.
Because you know everyone would want them in full lossless formats like FLAC and ALAC, etc.