Notwithstanding the increased functioning issues I've observed (as well as some of my fellow instructors) with many of the diminutive platforms which are chambered in these calibers ... (compared to larger center-fire handguns, and watching folks try to qualify with them on a CCW range over the years) ... I finally decided that they simply didn't offer the level of potential incapacitation I desired to have at hand in a defensive handgun. I realize that opinions vary, though ...
I know a fellow, now retired, who survived an armed encounter with a suspect who shot at him with a 9mm pistol, while he returned fire with a .25 pocket pistol. The distance involved was across an average city street, and it was late at night, so neither of them hit each other (or anyone else, fortunately).
That incident was reportedly one of several factors considered when policies were later revised limiting the minimum caliber of off-duty weapons to be .32 ACP ... which at least seems to lend itself to pistols offering better consistent functional reliability, and better ignition reliability comparing it to .22 ammunition, of course.
Myself? I decided that .38 Spl was the minimum caliber that met my personal desires and needs from that point onward. Yes, I know some folks that choose to carry .32 & .380 ACP off-duty weapons, and while I don't denigrate their choices, I choose otherwise for myself. Different strokes. There are, however, some quality pistols chambered in these calibers, and some quality defensive ammunition being offered.
FWIW, people wiser than I (meaning above my rank) are apparently in the process of changing our CCW policies to restrict permitted calibers to a .32 ACP minimum. I was told that qualification range interuptions for functioning problems with a lot of the smaller caliber pistols was a consideration in this regard.
Naturally, proper maintenance, or a lack thereof, can also be an important factor when folks bring their firearms to a CCW class, but if the smaller guns still seem to exhibit an overall tendency to a greater frequency of malfunctions, what are you going to do?
This is the sort of thing that unless otherwise restricted, remains to be determined by each individual, having spent a reasonably sufficient time studying and reviewing the issue for themselves, and then making their own informed decision. It's their lives, and perhaps the lives of their loved ones, that may someday hang in the balance.
I still think the caliber/platform issue often unjustly over-shadows the subjects of awareness, knowledge, skills & training, though ...
Just my thoughts ...