It all comes down to selecting the right tool for the right job.
If we're talking about survival in a disaster or any other sort of WROL (without rule of law) situation, then yes, a .22LR rifle with a few thousand rounds is an invaluable tool in your arsenal.
If we're talking about a discreet little pocket gun that will put holes in a mugger or other opportunistic attacker, or for use in a relatively low-risk environment (which applies to most of us), then yes, a .22LR or .22 short pocket pistol is a nice little tool to have. They also make great back-up guns.
But - if you're talking about an all-purpose gun for a moderate-to-high risk environment, meant to stop anyone from an opportunistic mugger to a drug-taking psychopath who isn't easily deterred by a little flash / bang / puncture...then you really want to go with a higher caliber firearm. Even guys who are hopped up on painkillers will stop attacking when their organs start failing due to massive tissue damage and hemorrhage.