You can rest assured that the folks operating the Predator are well aware of the cost of using one.
The article mentioned that they watched the insurgents for half an hour before zotting them. During this time the officer in charge almost certainly was checking in with the air operations folks to see if a gunship or fast mover was available for a (low tech) strike.
You are probably right. I just recall during the gulf war operating commnaders told Apache gunners to stop taking out $20,000 dollar trucks with $100,000 dollar missles and to use their chain gun more. Even in CCIP mode an F/A-18 can place a MK82 within 10 feet from 10,000 feet up. I agree and my statement may be premature and I withdraw my ascertion. Hurray for another smoking whole courtesy of the Predetor and a well used hellfire.