This being an aviation forum, ofcourse all discussion is centered around airplanes. But just for a moment forget them and as you leave for the airport, before you start your car press the brake. Remember the feeling. Then pump the pedal 5 - 6 times and observe how it feels. Stiffer, harder, shorter travel. What you have doen is compress minute pockets of air that exist in the brake lines. They are not supposed to be there, but they are. By pumping the brakes you create a greater pressure in the system and compress the air thus making the system less "mushy". So it makes sense to pump them before use, SOP or no SOP.