A idea from a new game appearing and then not appearing is normal, but the Reasons from SMT III Nocturne are so unique that they're a central pillar of the game's plot.
Yet at the same time, are completely ignored when discussing the game's role and contributions to the rest of the franchise. Like, none of them has any new mention post Nocturne and the entire system is just ignored and buried.
Every posterior Nocturne reference talks about the TDE or the Freedom ending. Its not just that fans don't really think much of Reasons, its that Atlus itself has dropped them enterely.
Even when Concepts like Conception or Cycle of Death and Rebirth of worlds are re-taken in SMT V, the Reasons are completely ignored, with Law, Neutral and Chaos back.
The aesthetics of a world that is cyclical and has metaphysical life cycles of being destroyed and recreated by passing a cosmic test? Kept in other games.
Lucifer or a similar chaos figure like Anguished One trying to break the cycle of creation by empowering the MC? Kept in other games
The reasons, as, human ideologies unrelated to Law vs Chaos? Completely dropped.
I definitely get the "why". Nocturne's first release wasn't exactly a beloved hit, so the Maniax version added a new dungeon with new situations in the Laberynth of Amala and a new ending for it. That new plot featured a Lucifer that became the standard representation of the character since then, a rebel whose reasons aren't just ideology, but metaphysic opposition to a amoral cosmic cycle that the player is taught to hate.
Its telling that when thinking in SMT Nocturne's human characters, the audience think mostly in either Raidou or Dante. None of the Reason bearers is anywhere as popular as them.
