It sounds like a very big oversight in my opinion because it happens so arbitrary. Ie. You could be in a fight and reviewing everything (music thumping to get you ready to battle), and then as soon as you perform an action it goes dead quiet and never comes back. At the very least, if you need a sound channel for a sound effect, play it, and then resume the music. But that's just my opinion.
I would be very interested in seeing if someone could produce a proper patch for this as well. While I will admit I am no PCE/TG16 hacker, from the face of it it seems like a trivial mod to perform, given all the complicated stuff people have successfully done before. Again, in my humble opinion of course.