I think Lucas McCain hit all the points and for me personally, it's got to do a lot with the shortage issues that lasted for years and .22 not being a good self defense round.
That's not to say I'm not shooting .22, I am, I shoot it more than anything else. The NAA Minimaster, SR22, and soon the Charger... they're all getting a lot of range time, more than my centerfire guns. I just have nothing more to say about them. I can't go into reloading or how to make them more accurate because I'm limited to what quality I get in the box of ammo I buy and this is one of the major reasons I'm not into .22's like I am other cartridges.
As to why people aren't talking about them? I think there's a lot to be said for first time gun owners who want something for protection and .22 isn't it, a .38 or a 9mm is. Nobody will ever recommend a .22 over a centerfire and even non-gun people get that a .22 is smaller than 9mm or .38 Special and not as powerful. First time owners are not going to be willing to spend $350 on a decent .22 pistol, then spend another $300 on a budget 9mm on top of ammo, mags, holsters, etc.
To me, .22's are fun guns for shooting with some ability for self defense or small game getting. All of my .22 revolvers I have or will be buying have spare .22 Mag cylinders, so they're really .22 Magnums. My Charger with the brace is really just so I can shoot a shorter barrel .22 rifle off my shoulder without an NFA item that isn't legal in my state. It's short OAL could find use in my cramped apartment for home defense, but it's really just something that's a 10/22 based gun that's for SHTF and is a fun range gun that's also a big finger to the ATF.