1/3 of a fighter by weight is life support for the pilot, plus controls, ejection seats, etc. Scrap all that and you can do more for the same weight, or make a lighter, longer-ranged plane.
Plus pilots get tired, spooked, etc. Drone operators can switch over to someone else in the room and hit a bathroom and smoke a cig, and AI doesn't even have that problem.
AI can also, in theory, react faster, and is not constrained by high-G maneuvers, that would push a pilots blood out of their brain to their feet. You can find Stroke-3 vids on youtube, which is a pilot in an F-16 (Stroke-3) dodging SAMs during Gulf War 1 -- you can actually hear him strain and groan under the high-Gs.
EW and Jamming are also a concern, and controlled drones are ultimately dependent on someone on the ground being able to see and react. Most drones have an autopilot function if they lose contact, but once ECM and ECCM start going hard it may be hard to control them; they'll need to be autonomous, sort of a more tactically flexible loitering munition.
i.e. can be deployed 100,000 times at once; doesn't need a stable internet connection; can fit into a drone; if civilians are hit, it's only a software-error, not a war-crime.
you wouldn't say that about a bullet or a missile -- the morality isn't negated, it's moved up the chain to whoever operates the device.
I make this point because I find the thought that drones somehow negate moral responsibility to be wholly irresponsible and destructive, not as a pedantry.
But in practice, the lack of morals will be a strong incentive. One one hand we have commanders who may want to get away with war crimes, and on the other hand are autocratic regimes, that don't need as many like-minded soldiers to commit large-scale war crimes.
