Here's a quote by Chuck Taylor in his "Combat Corner" column from the August 2008 issue of Combat Handguns.
"Though too often overlooked these days, in the high-speed world of combat pistolcraft, control is a major factor and is as important as accuracy, stopping power and functional reliability. It doesn't matter much how accurate or powerful a given load might be if it recoils so much that the typical shooter cannot "deliver the goods" to his target quickly enough or accurately enough under stress."
He's speaking about the difference between standard pressure and +P in .45ACP loadings, but the comment applies in general as well. Based on what I see at the range, there are a lot of people who would be better armed with a .22 than the hand-cannon they've picked primarily on the basis of caliber reputation. At least they might be able to hit something with a rimfire pistol.
According to Mr. Taylor, one needs to pick the best balance from among the following characteristics because all are equally important.
(The ability to hit one's target.)
(The ability to fire repeatedly at a reasonable pace without significantly degrading accuracy.)
(Does the gun, in your hands, work consistently?)
People like to focus on caliber because it takes the onus off them. If they can convince themselves that handgun effectiveness is measured by numbers on an ammunition box then they don't have to feel guilty about not practicing to gain and maintain a reasonable level of proficiency.