...now seems to be via a value-based pricing system/fare structure.
The LCCs with their simplified fare structures have been seeing their yields and average fares rise (especially jetBlue), while the exact opposite has been happening to the network carriers.
As strange as it seems, more and more, people are willing to "pay more and search less for assurance of a reasonable (sub $300) fare".
Often, people will be willing to pay $150 each way for a midcon trip on Southwest even when a little searching on Orbitz or other price-comparison travel sites can provide a network carrier fare of $200 RT on an equivalent flight. People value the reliability of LCC fare structures!