My reading over the years leads me to believe this horrible hit ratio is the result of the adoption of the so-called "wonder 9s" by LEO agencies many years ago. When officers carried revolvers, I think the rounds-fired-to-hit ratio was 2.x while the current ratio is a multiple of that number. This was with officers carrying .357 Magnum handguns with much greater felt-recoil.
The poor hit ratio you note is one reason I discount the "shot placement" argument many folks rely upon for using a 9mm over something larger. While it is certainly accurate to state that shot placement is important, getting a round into a desired location to stop an attacker seems to be more a matter of luck with many people, based the poor hit ratio with higher-capacity handguns. Remember, one of the primary arguments justifying a 9mm over a 45ACP is faster follow-up shots. This argument seems to be put forth in tandem with the “shot placement argument, but they are somewhat contradictory.
If shot placement is critical, and I believe it is, then the first round or two fired need to be put where they are most likely to prevent you from being killed by a would-be murderer. It is the rare person indeed that cannot fire the first round of a 45ACP just as accurately as the first round of a 9mm. The mindset should be “put the first round where it needs to go, not “I have 15 rounds to get one on target.” I know, I know, that’s an overstatement, but the concept is valid.
In my view, a higher capacity handgun is desirable in the event you are attacked by multiple assailants, not to offset poor marksmanship.
Chas.