The 28 Type IIIs carried only 56 torpedoes between them, while a much smaller force of fleet destroyers could carry comparable numbers. Contemporary torpedoes were largely point-and-shoot weapons, so a spread improved the chance of a hit. The Hunt's centreline launchers also required the ship to turn beam-on to fire, exposing it during an approach. The design judgment here is that retaining the extra 4-inch guns would have been more useful for the class's intended work.
Notable Point · 42:17-46:59
Why two torpedoes were a weak destroyer weapon
Unguided torpedoes depended on salvo volume, so a two-torpedo Type III Hunt had to take substantial risk for a limited chance of a hit.