Look, I started business flying in 1978 when fares were regulated and point-to-point fares were the same for all the airlines. I travelled with a stack of AAirchecks which any airlines would take. I could walk to the gate of any airline, ask if there was a seat and literally write my own ticket. While I used AAirchecks, I rarely flew AA then. I was Eastern/Delta N/S out of Boston and TWA transcon/TATL. If a meeting ran over and I needed to miss a flight, I would look up the next flight in my pocket OAG, call my secretary (yes, that's what we called PA's then) and have her book me on it.
But de-regulation and loyalty programs totally blew up that model and we've been in that new model since then. Frankly, the "new" economics of AA (and all the other airlines) have pretty much been baked in since then (say early 1980's). While I agree at your comment that it is irrational on a tactical level, the airlines have pretty much concluded (and colluded) to make the rigidity of that irrationality a strategic cornerstone of their pricing philosophy. De-regulation opened the door to tiered pricing and the only way that worked for the airlines was with reducing flexibility.
This new model is less flexible but it delivers great value for a smart/savvy traveler who is willing to play the game.