They are way more accurate and inflict significant psychological pressure. You know you wont die fast when they hit you, the explosive is to small to do that, you cant outrun them, shooting them doesn't work 90% of the time, AA cant do shit against them because they look like birds to it.
The moral crushing potential of drones is frightening but good as long as used by the right people. Drones are the artillery of the 21st century. (although artillery is more effective for stationary or heavy targets)
Every type of weapon is a tool for a specific type of work... However you can use most tools as a hammer (shooting soft targets)
Don't need that for war, the psychological damage is important.
The Germans literally put sirens on their hunting bombers in WW2 to inflict fear in the people hearing it (https://youtu.be/Evi8YYDywL4)
It would be interesting for assassinations or terrorist though...