I am sure that everything the pilot mentioned is part of the equation, but if this truly is the real reason behind the baggage fees then why didn't they start doing this years ago? Seems to me that oil/fuel prices were certainly a very major factor and/or the main catalyst behind it.

Also, was United the first airline to add the baggage fees? As I recall they were not. Sounds like UA was following the lead of other carriers in an attempt to make some extra money vs. acting independently on data obtained through a study of checked baggage habits.

I'd also like to point out that commercial carriers like UA have been hauling cargo for a profit for quite some time. Maybe I'm missing something but I can't imagine that the difference in the average number of checked bags on flights has changed so dramatically "post-fee implementation" as to allow for a huge increase in cargo capacity. Again, if it was that big of a deal I'm sure they would've started this a long time ago. Also, adding more cargo means heavier planes (especially if their goal was to chase checked luggage into o/h bins rather then discourage it entirely) and heavier planes means more fuel=more operating expenses=less profit. Obviously, a 200lb cargo package is cheaper to transport than a 200lb human, but if that 200lb human has another 40-50 lbs of carry-on luggage than that margin narrows a bit.

Bottom line here IMO is that the pilot you spoke with was doing more speculating than recitation of factual information.