Nyquist gets misused all the time for justifying a lower sampling rate. The maximum reproduced frequency is only part of the equation when reproducing multi channel sound. quoted from
http://www.24bitfaq.org/ :
0.3.5 Which is said to provide greater benefit to the listener over conventional 16-bit 44.1/48kHz recordings: Increased sampling rate or increased word length?
A: Increased word length. From Ken Pohlmann's "Principles of Digital Audio," 4th edition, p390-391:
"The use of high sampling rates such as 96 and 192kHz may seem unnecessary. In rare cases, a person may be able to hear frequencies of 24 or 26kHz, far below the cutoff frequencies of 48 and 96kHz [for 96 and 192kHz sampling rates respectively]. In most cases, high frequency hearing response is below 20kHz. Thus, for steady-state tones, the higher frequency response may not be useful. However, it can be argued that high sampling frequencies improve binaural time response, leading to improved imaging. For example, if short pulses are applied to each ear, a 15 microseconds difference between the pulses can be heard, and that time difference is shorter than the time between two samples at 48kHz. Some people can hear a 5 microseconds difference, and that corresponds to the time difference between two samples at 192kHz. In theory, this high sampling rate may improve spatial imaging. Thus, it may take two ears to distinguish between a recording at 48kHz, and one at 192kHz."