Full auto is just going to run through your ammo at the expense of accuracy, reliability, and maintenance time and costs. Nobody is going to be providing covering fire with a fully-auto machine pistol, the ammo capacity just isn't big enough (and then think about cooling and mechanism reliability when putting more than a dozen through a handgun). These things are for raids and assassinations, where collateral damage isn't a big deal but taking out the target is.

There are many better guns to fit this exact niche. HK& MP7 or B&T MP9, for example.

Full-auto anything that isn’t a chaingun is basically a meme anyway, even for rifles and friends.

What is NOT a meme, and is useful, but counts as fully automatic, is three or five round burst mode.