Why no music in current Lix: This is largely historical.
In the earlier years, I found that I was playing my own music in the background anyway. This fits into a workflow where you play for 1 minute at most, then terminate and work on the code again. At this time, there were no regular users who would eventually come back to me and strongly suggest music.
Thus, including music became very low-priority. There was the Dumb plugin for A4 to play tracker music, but A4 didn't come bundled with it. I never looked deeply into it. Also, I wouldn't want to ask the composers of existing music whether they'd be fine with releasing as public domain. This was the rationale around 2008, I have put off caring about it since. It's one of the problems from wanting to release absolutely everything as public domain. (It shouldn't be a problem, rant available on demand.)
I recognize that lack of music is immediately obvious to new players. Much more obvious than whatever details I care about, provided the game runs reasonably smoothly for them.
Including ogg is fatter than including tracked music. That isn't problematic yet, because there isn't yet a ton of music to include, and there will be several solutions anyway. (Include only some pieces, include lo-fi version, ..., make hi-fi version available as extra download.)
-- Simon