But I’ve seen none with guns attacking infantry.
Why is that? And will it change?
Then you'd need to aim... more than once with each shot rotating the drone. And you need to aim either semi-automatically or manually with a non-trivial delay.
None of those problems apply if you're just dropping something straight down.
Why bother with all these technical hassles when you can just use bombs which is way easier and probably more effective at killing.