If you look at the history of using aircraft to deliver weapons, the progression of drones as a weapon makes complete sense.
It all began with pilots dropping explosive devices from airplanes.
Then a machine gun was mounted on a plane (the French were first to do this).
Sure, we have military drones that can do these things, but in the world of guerrilla warfare and terrorism, cost effective methods are employed to advance a movement.
Commercial drones or more simply drone “kits” are going to be a huge issue in the near future.