Look, if you think they are cool and want to shoot a .22LR AR-15, then be my guest and go for it! Have fun. Knock yourself out. But for goodness sake, stop pretending that you are doing something useful to training with it.
What a horrible attitude.
Shooting, like any other skill, only improves with practice. To suggest that shooting more (even rimfires) can't help you improve the skill, is just ridiculous.