Upgrading to a 24/48 standard would be fantastic. It won't change what's already been recorded at 16/41.1, but at least it would be something.
24-bit would definitely get the tracks more dynamic room, which is super important on the jazz and bluegrass tracks.
But upping the bitrate to at least 48k would make all the pitch/time shifting function so much better. More samples = potentially fewer artifacts when transposing or time stretching the tracks.

So either change would be a HUGE step in improving BIAB. However, it would also really only affect the Audiophile users. (Can you even make a 24/48 mp3?) And I'm guessing that's such a small nitch of their users - plus it would exponentially expand the size of the files required - that they probably don't think it's a cost-effective idea.
But it would greatly improve the audio quality of their product.

Catch-22.