Ugh. Just because it looks like a weapon an army might use, does not mean that it is a weapon an army would use.
For example: these two rifles are essentially the same thing. Semi-automatic .22 rifles, made by the same company (Ruger). One of them just looks "scarier".
View attachment 3216 View attachment 3217
Now to answer your question, I use them for hunting. I'll use an AR version of a .22 to shoot things like rockchucks, gophers, squirrels...small things like that. It's nice to not have to reload as often, and AR types are very accurate, which is nice for small game. I would use a .223 AR version to shoot wolves or coyotes. Fast animals where it's nice not to have to reload with a bolt or lever action in order to shoot again, because they can get away from you quick.
Now tell me this, what is wrong with having them? Because people abuse them? Better get rid of alcohol too then. Hell, we better get rid of cars. Removing things just because people abuse them is not the right answer.