if i could choose just one thing, just one tiny little thing
support for loopstart/loopend/looplength in ogg files
Technically, you could use music bricks and events for that, like, have an event activate a music brick to play the 'intro' OGG that's a song up until it's loop point where you'd then have the 'loop' OGG play after the intro ends, which you can use Audacity to get the length of the intro in milliseconds so you know for how long to delay setting the music brick to the loop OGG
Then you can have an event that sets the music brick to the 'outro' OGG either whenever want, or you can multiply the loop OGG's length by how many times you want the loop to loop, then use the end result of that equation as the value for the delay on setting the music brick to the outro OGG
It might be a bit of a pain, especially since it takes up 3 Music datablocks per song, but i think that's the closest we'll get to 'dynamic music'