Exactly. When you're down to single digit pressures or barely above, 2psi can be the difference between debeading your tire and not. I don't trust a dump valve to be that accurate.
Also, I think people are underestimating the massive difference between airing down by pushing in the schrader and by removing the core. I bet I can air down my 4 tires as fast as your Stauns anyway, and I only have to walk around my truck once. Different strokes for different folks, but I don't know that the thread on style are "faster".