As to why it appears so much in other works is hard to say without studying more than I care to right now. If I were to make an educated guess I would say that in Beethoven's time this motif would have sounded familiar to audiences. This was before Berlioz and the idee fixe, and Wagner's leit motif but this doesn't mean that there weren't familiar tunes and progressions that reminded people of certain things...like hearing Taps being played by a single horn reminds us of the military...or military funerals. As it has already been suggested...it's meant to sound like a horn fanfare.I know of no nickname for this particular progression but there may have been one in Beethoven's day.