first: actually it was a well known tactic to throw grenades into houses, bunkers, etc. even if you didn't see an enemy run in there was SOP (standard operating procedure) because it's better to waste a nade than get capped in the arse.

second: shitguns weren't used all that much in WWII.
and the reason people whine about them is not because they are powerful but because other guns are weak compared to real life. think about it, if a shotgun takes 1 hit to kill and a Tommy takes 5 whos going to win if two enemies of the same aiming skills run into each other? It is quite annoying, and not realistic to have a guy that you shot 3 times with a Thompson just run up and shotgun you. The other guns are so weakened that the shotgun has a distinct advantage and sooner or later everyone will use one on a stock server. what fun is that? If you want to use nothing but shotgun go play doom or quake.

third: I believe that bazookas were inded used as anti-personnel, but only for clearing out houses and bunkers, like a long range grenade.