After looking into the applications of 'b'rov am' and thinking about this issue further, I can refine the critique.
Had a big deal been made about the fact that 20.000 people were in a gigantic room, and while everyone was davening shmoneh esrei you could hear a pin drop, then I would have been really impressed and inspired.
Interestingly, MB applies 'rov am' to tefilla be-tzibbur (i.e., davening 18 together) but not to 'dvarim she-bikedusha' (kaddish, kedushah, barchu) which makes it entirely consistent w/ the mishna in Brachot. Acamo"l.
And, behold, the LORD passed by, and a great and strong wind rent the mountains, and broke in pieces the rocks before the LORD; but the LORD was not in the wind; and after the wind an earthquake; but the LORD was not in the earthquake and after the earthquake a fire; but the LORD was not in the fire; and after the fire a still small voice.