Although that is pretty good, I think the few standard formats that are already supported are sufficient, and there is really no getting around the MP3 thing. I was speaking in IRC with someone about a week ago and we were discussing this issue. He was experienced in creating codecs and into the whole audio thing, and he was a little more knowledgeable on the matter than I. He basically confirmed what we already knew about there being no free way to use the MP3 format.
Basically, I really don't want to have to purchase a license, and neither do I think we really need to. Other formats are actually better suited for games anyway, and since there is already the ability to stream them, MP3 really doesn't have anything to offer, except maybe the fact that there are already existing resources using the format. I don't even think that will be any great obstacle since there are plenty of free and easy ways to quickly convert them, and I am sure there will be many people who make it a task to do so for everyone and upload them.