Firaxis/2K was already paying royalties for many other things in BNW
For example?
And, let's get some perspective here. Firaxis wouldn't have to hire a professional orchestra and rent a fancy studio at some absurdly high fee. A decent university band in a basic studio could produce far better music than the crap that's currently in the game and they'd probably do it for next to nothing because of the good publicity.
But if not, well, there's plenty of free music out there. For instance, see
http://www.classiccat.net/. Some of it is under non-commercial licenses but much of it isn't.
Well, I just have a few problems with this. The university band thing, well no. That type of outsourcing can seem potentially unreliable (irregardless of the truth, unfortunately). Management would probably not be happy about it anyway. Firaxis is not a small indie developer that can do whatever it wants...
I'm not so sure about the link. A lot of it relinks to the PianoSociety and can't be used commercially. (the only exception I stumbled onto was Vivaldi's Spring Concerto, but that was old record quality and still not available for commercial use). None of the content is hosted on the site. Unless you can link to a better repository, I have my doubts about how viable this is.
My other concern is something I just realized. The music are complete pieces. You would have to fade out all the pieces. You may think this is easy, but it'd be extremely difficult to do this cleanly (ie. as if the band stopped playing as opposed to a regular fade out).
Then there's the issue of diversity and consistency. Everything I've seen so far is western. So you'd end up with a bunch of excellent western tracks (if you can find them at a non-vinyl record quality, and even then you might still need a bunch of lawyers to make sure everything's legal cause of America's sue culture), and a bunch of non-western tracks in midi format. Unless you expect Firaxis to go running around to find a Traditional Thai, Japanese, Chinese, Indian, Native American, etc. orchestras. Probably not worth the price too, since it's just one or two 10 second pieces each.
and that part I don't think a university band could manage properly (especially since even Wikipedia seems to be lacking a lot of non-western pieces).
If anyone says "I don't care about non-western pieces", well, may you be cursed by the spirits of everywhere but the west; and may Gandhi nuke you all the time...
tl;dr: Let's just say it's stuffing in a bunch of midi files seems much easier; and the alternative ain't worth the effort.