New Amazon music streaming service and Nyquist sampling theorem
Bit rate should not be confused with sample rate.

Other things being equal, a higher bit rate mean more bits per sample, which means less noise energy per sample added due to the quantisation process.

Nyquist says only that you need more than 2x the bandwidth to reconstruct the original sampled waveform. He is silent on how much more you need. The more in excess of 2x the bandwidth you have available, the less work you need to do when anti-alias or reconstruction filtering. A reconstruction filter from 48kHz (a common digital music DAC rate) requires about half the resources that one from 44.1kHz needs, as resources scale by roughly the reciprocal of the width of the transition band. Alternatively, this could mean that, for the same resources, the filter from 48kHz can be made 'better' than one from 44.1kHz.

Those are facts. When we get into subjective audio quality, and whether 20 bits actually sounds better than 16, or 96kHz sounds better than 44.1, then opinions generally prevent rational discussion. However, 'more stuff' generally does help shift product into some sectors of the market. 

For the record though, when I was making some vinyl to CD transfers for my Mother, and cleaning up surface noise and muting between tracks in Audacity, I was very surprised to find that a 30dB SNR was all that I needed to hear music as essentially 'noise free'. That's me though, I've probably grown a bit cloth-eared with my increasing age.