Why don't we see more of the Steiner 20X binos being used?

Probably because they are giant. The Vortex Kaibabs are slightly lighter but a smaller package and cheaper. Most people either pick something smaller with less magnification, or just buy a spotter with variable magnification.

As mention in the other thread, most people are choosing binos over spotters because its a smaller, lighter package and they can get good results with 10-15x magnification.
 
I had some M1050R binos a while back, and the FOV kind of sucked. Tripod mounting solutions were non existent, impossible to use with glasses, etc. Their design is basically a bit outdated ergonomically. I ended up using my Athlon Cronus binos more than my Steiners and ended up selling the M1050R.