>>Why do you think so? UAVs can be just as expensive as manned fighters.<<
Because manned fighters can hurt the MAN/MEN in the cockpit. We need them dudes to do stuff that requires a human in the seat at the moment.
Passive hunts for cowards can be regulated to robots.
A single pilot who gets hit by flak or a lucky SAM is too high a price to pay for simple Search and Destroy Weinies.