The skill set for a Pilot/NFO/Crew is no doubt going to cost more money... however I would say that its something different to say that a pilot is "worth more" than an infantry officer. just my opinion. Were you speaking in terms of training costs or battlefield assets?
I wouldnt go so far as to say money is the only cost. Think of how long the pipeline from start to finish is to be an effective Infantry Officer compaired to an Aviator. Your not just a bigger hit so much as "Damn there goes a good chunk of change..." but they have to replace you and the pipeline to do so is a lot less capable of accepting a sudden massive loss. And that combination is the justification of pulling pilots out of the line of fire faster then Infantry. Only so much money to R&D and implement a program, so we gotta go with the one that shows the greatest cost to benefit.