Long ago in the early 90s, Lucas Arts created the "iMUSE" System (interactive music engine). It was able to change the background music in dependancy of the player's situation and was used in many games like X-Wing and Tie-Fighter. So this Idea is nothing new and I always liked it. But in fact nowadays we´re not talking about (primitive) midi-tracks but a combination of voices-, sound- and music-samples and this is a more complex issue and not as easy to achieve as in the iMUSE example.
If anyone feels free to program a next generation "iMUSE", the Larians surely will appreciate it <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />