Higher resolution recording is often done when making field recordings for various reasons.
While I can't exactly answer your question regarding SoundTap's higher sample rate options, I think it would be good to consider that any internet/radio stream recorded via SoundTap on a computer will be mp3 in origin,
so while I will often set my streams to save as .wav 16/44.1, there is no sonic advantage to be expected. (I assume you already realize this per your above statement 'makes no sense...')
If the end use is playback on an mp3 player, it makes sense just to record as an mp3 (320 CBR is what I'd recommend, although most internet/radio streams are of lesser quality)