1) Those are the largest calibers that you are proficient with.
Little bitty guns are HARDER to shoot well, not easier.
Now, a duty-size gun in .32acp would be an easy one, I think some Bullseye shooters have large guns in .32 for the "centerfire" category, but mouseguns are advanced weapons, not beginner's guns.
2) You just want a tiny gun that doesn't take up too much room in your pocket, or purse.
This is a concern for the "I only carry once in a while" crowd, or those desiring extreme deep concealment for whatever reason. Once you start buying quality gear and dressing around the weapon it becomes much less of a concern.
BUT ... for some reason the endless search for a "light, concealable, flat, big-bore, inexpensive, accurate, knockdown power having, easy for my wife to shoot, not too loud, scary-looking, light-mounting, laser-gripped, easy-to-maintain" gun continues, for the purposes of "carrying when I go to a bad neighborhood". It goes along with the "Glock vs .45" debate and the caliber wars, among people who are trying to solve their software issues by buying hardware.
Amateurs argue equipment; professionals emphasize training.
Damn right, the caliber wars are a dead giveaway of amateurs.