The 8-bit is actually reasonable: they have one output per possible value, so 16 bit would mean 65k outputs... They could probably do a secondary step that adds

The 8-bit is actually reasonable: they have one output per possible value, so 16 bit would mean 65k outputs... They could probably do a secondary step that adds less significant bits. The low samplerate is probably because it's originally used for speech, and a lot of speech databases are in 16 kHz.