Basically, what seemed to be an act of "let's screw over non-seasonal players" at first, was a necessary action to sacrifice one Era (era 5) to ensure the integrity of non-seasonal gameplay going forward (i.e., era 6).
Eras were never really designed to be a “mirror” of Seasons, though as they coincided frequently in the past, it’s easy to see how that became the expectation.
We’re philosophically discussing the place of Eras going forward, namely what they mean to us as well as players and how we’ll handle rolling them in the future. How (or even whether or not) Eras are affected by patches is a consideration and is why we changed the way we rolled Era 5. Changes in 2.4.1 will affect the performance of multiplayer groups, potentially bringing overall group records down, and we wanted to avoid a situation in which Era 6 could have had multiplayer records effectively locked at the start of the Era. This is definitely something we could have communicated earlier and more clearly, and we’re certainly going to strive to do so in the future.
Needless to say, the community’s feedback has most certainly been heard on this issue, and we’re evaluating our process to try to find the best of both worlds going forward.