F-15s have pulled well over 10g without killing the pilot, however it damaged the airframe beyond repair. An aircraft that could routinely pull high-G manoeuvres would have to be reinforced to the detriment of its weight (and thus its size/range/load capacity) and cost.

The expected direction of drones is as loyal wingmen (i.e., to carry sensors, weapons and/or fuel) and to be low-cost (i.e., disposable). If your drone costs more than an F-35 you'll want to get it home again, whether there's a human inside or not.