Remember two things.

1) Existing audio are moving to 24 bit, since 16-bit CD-quality audio gets close to square wave at low volumes. It has less dynamic range than the 14-bit competing CD technology that lost out. For classic music, you have have very high dynamic range directly in the sound material. For film material, it's even worse. Movie sound just have to use 20-bit or more or you wouldn't be able to handle silent suspence and at the same time switch over to a volcano erruption. With DVD and DVD-AUDIO having 24-bit content, you can't avoid having sound cards designed for playing 24-bit audio. Obviously, no card is even close to recording 24-bit audio. But a card that can capture 20 bit audio with the noise level at 18 bits still produces way better data than a 16-bit card. And it really is useful to be able to capture one or more bits below the noise level - post-processing will be able to make use of some of that information. Downsampling 192kHz -> 44kHz is such a postprocessing step.

2) The recording industry does not make use of 16-bit audio other than as output format for a CD. The session recordings, mixes and master recordings are never 16-bit. And the equipment does not work with 16-bit audio.