It's got absolutely nothing to do with "morality" it's simply supply and demand economics. Doesn't matter if the commodity is airline pilots, or tins of beans - when there is a massive over supply and not enough demand, the price of the commodity goes down to meet the market.
But while we're daydreaming, can I ask why you drew the arbitrary line at pay-for-rating? There was a time when airlines paid for instrument ratings and put you in an airliner on fantastically high pay as soon as you graduated from school. Hell, there was a time when they paid for all training costs right from day one. Let's return to those times, all we need to do is make a plan to ensure that nobody on earth will sign up for ab initio training unless it's fully paid for. That will surely screw the evil airline management over
Of course everyone will need to stand together on it for the next 20 or 30 years before the shortage really starts to bite ... but hey it's a small price to pay, I'm sure everybody would understand, the young guys won't mind staying unemployed and waiting until they're 40 or 50 to get their hands on those shiny jets, after all it's for the good of everyone right?
Extreme I know but you see how silly it is to claim the high ground of "morality" in the business world.