The trouble with drones is also their main strength. They are remote control robots. -Expendable and obedient.
If Gaddafi had drones they would have bombed civilians as ordered. Libyan pilots famously defected to Malta when they were ordered to fire on their own citizens.
The Soviet Union may still exist today if it had a drone air force. At the climax of the 1991 coup, when the Red Army and the KGB usurped the Communist Party's Premier, they ordered the Air Force to bomb Moscow.* They refused. The USSR dissolved shortly after.
Drones would have bombed Moscow. They make no moral distinction between targets. A Human pilot can rebel against insane orders, even if the orders are perfectly legitimate. Drones can't even distinguish between legitimate or illegitimate orders let alone make moral judgements on them.
Last week it was reported that a stubborn virus had infected the ground control station at Creech Air Force Base in Nevada. No matter what they do they havn't been able to wipe it off. The report suggests that it's a simple keylogger virus that records keystrokes. It could have conceivably been much worse however.
The Stuxnet virus that attacked the Iranian nuclear weapons program actually took control of centrifuges that were being used to refine weapons grade Uranium. The ingenious virus subverted the display screens of the centrifuges so that the operators had no idea what was happening. The virus then set the centrifuges to destroy themselves by spinning out of control.
Iran coincidentally has its own drone program. Like the rogue centrifuges, a drone will simply do whatever it's commanded, be it virus or human, friend or foe.
There are other limitations too. Drones are primarily suited to asymmetrical warfare. Insurgents and Jihadis will not have surface to air missiles or viruses of their own as of yet. They can't jam the signal to the drone with noise or knock out the signal source either. An advanced hostile state may have these capabilities.
Some suggest that drones could be a viable alternative to the F-35. This is not a serious suggestion. It would be like suggesting that a torpedo, a sophisticated remote controlled drone-like submarine, could replace a ship. No.
This is why a drone fleet will always have a support role that augments
real fighter jets with real on-board pilots. Drones are merely tools
and cannot replace fighter jets or bombers as the mainstay of a
serious Air Force. Anyone who thinks this simply hasn't thought it
through or is making this suggestion for political reasons.
*I'm not able to locate an online reference for this but I saw it on a Frontline documentary about the fall of the USSR years ago.