I believe the primary difference between the pilot profession and the medical and legal professions are that pilots tend to be "standardised" to the point where there is little identifiable difference between a "good" pilot and an "adequate" pilot - at least not to the bean counters.
In contrast, the highly regarded/highly experienced surgeons and lawyers get to pretty much write their own salaries (in private practice at least) - whereas the mediocre or non-ambitious, or those in the public sector, are paid poorly in comparison.
Yes, years of training and experience are rewarded in some professions, but not all. I know a surgeon who does very well thank you very much. I also know a highly regarded CEO who does not, simply because he chooses to work for companies he wants to work for rather than who will offer the highest salary. I also know several very low paid PhD graduates.
It took me nearly 10 years to get into the back seat of a jet and a further 15 to get into the LHS of one. I don't feel overpaid, nor do I feel underpaid. My CEO keeps telling me I'm overpaid - at least there the feeling is mutual. Some pilots get to the top a lot faster than that, some slower. Big deal. Many earn a lot more than I do too, many less. I think its worth it to keep up the fight or we'll continue the race to the bottom.