If you don't personally enjoy shooting .22s I can only think of two possible reasons to get one.
1. If you believe it likely that you will have reason to introduce newbies to shooting -- especially a timid person or a wavering anti-gun person. While it is not required to begin a newbie with a .22 its hard to deny that a western-styled, .22 revolver is probably one of the least intimidating guns on earth. It goes "crack" instead of "BOOM", nothing whooshes at your face, and it doesn't try to leap out of your hands. Its downright friendly.
A .22 semi-auto, like my Mark III may be easier to actually shoot well than a .22 revolver, but the magazine, slide, and general techi-ness makes it more intimidating to someone utterly unfamiliar with guns. But its great for newbies who aren't scared of guns.
2. If you have reason to suspect that you might have an injury or develop a medical condition that requires "no recoil" and live in a state with a waiting period on gun purchases.
Otherwise, if you're happy with what you've got you don't need to spend money because others think you should.
However, you might consider the challenge factor involved in bullet diameter. My DH can obliterate the X from an NRA B-8 target with his 9mm if he hits it 3-4 times. I have to hit it at least 8-10 times to do the same. So if we fire the same number of bullets I have to be a better shot to accomplish the challenge.
Whether that matters to you or not depends on whether you enjoy upping the difficulty in that fashion.
