What specific term of the program was violated by AS introducing a new fare basis which has different features? You can look all you want and you will not find it. In fact, you will run straight into the disclosure that the program may be changed at any time (although the program has not been changed at all).

However, for most, they are a bad deal. Whether you ordinarily pay a change fee or not, these tickets are wholly inflexible. If you need to make a change or cancel, the ticket loses all value and you simply buy a new one.

This ship sailed 6 years ago when DL introduced the fares and started expanding them because they are highly profitable and many customers like them (because they are cheaper and they want to save money).