Illegal Explosive Devices are WAY more effective than legal semi-autos.
Vastly more bang for the buck, when successfully inserted into the most damaging position that can be achieved under the circumstances.
Think of these suicide bombers as moving delivery systems for highly destructive devices with their own built-in and unjammable guidance systems, operating in a manner that makes their early detection and interception highly unlikely.
In the latter part of WW II, Japan was sending out the Kamikaze pilots, in what was virtually a winged bomb, with the pilot as the guidance system, who could sight in on a target with pinpoint accuracy impossible with the mechanical guidance technology of the time. If the deck gunners did not take the diving suicide plane out quickly enough, the carnage was really terrible aboard ship.
Imagine a dozen of these zeroed in on your ship.
Once the kamikaze took off, there was no such thing as “return to base”. Hard to fight that mindset.