Agreed. Firearms are considered very effective, even though bullets can't track their targets. Those torpedos were not designed to take out fast attack subs or PT boats. They were made to take out relatively slow ships, like Aegis cruisers and lumbering giants, such as carriers. A supercarrier IS the most effective way to project power, but they were never built for any kind of evasive action.
Actually, the "Squall" was developed as a close-range "knife fight" weapon for combat between submarines. Those boats are fast and maneuverable enough to warrant use of a supercavitating hyper-speed weapon. By the time the sonarman hears it, it's too late to evade it.
Another issue is that the torpedo's design limits its potential for maneuvering. Turn a bit too much "sideways" and the bubble collapses, destroying the torpedo. The thing would have the turning radius of a Bonneville Salt Flats racer at 200+ mph.
The design also creates an enormous amount of noise, so any submarine using such a weapon would get one shot before Hell rained down on it. Now, if we were to build a similar toy with "swim-out" capability, that would really turn subsurface warfare on its ear.