There are limitations to the technology, but in right scenarios it is perfect.

One should not use it on attack, when people need to distinguish between a soldier and a civilian.

But on a defence, when you need to keep a certain area empty from enemies (and there is nobody else but enemies incoming), then it resembles the usage of mines, only better (both in terms of efficiency and safety/callback/disarm).

Another scenario or cutting the logistics. If you know that a road is only used by military, then letting the automatic drones watch and engage is a great idea.