Judging from Rob's post on the subject, I would guess that it has nothing to do with 64kbps.

Seems very odd to me that they would use such a format for a computer game. I am no audiophile, but 64kbps sounds awful to me, and CD-quality sound seems more the norm today for games. I assume they used 64kbps to save CPU, but it seems like they could get much better quality if they didn't use a format with aggressive compression like MP3. On a CD distribution they should have room to spare.

Corby
SN#320, 6-Gig Blue