I would say that, in fiction literature, apparent didacticism is either purposeful and intense and sincere OR it is puckish or a narrative trick or unreliable/(non)-collusive. Sometimes a bit of both. After reading Thomas Ligotti's THE CONSPIRACY AGAINST THE HUMAN RACE, I have gained the impression that his fiction has become more like the former than the latter.
On a general level, I know that at least part of me somewhat resonates with anti-Natalism and its sensibility - and I would think that a 'l'art pour l'art' approach is something that suits any expected short-termism of finite life, making one relish the hedonistic and visionary as a bankable asset before existence is snatched away in pain or darkness. On the other hand, didacticism or a roman-a-clef approach seems more thrusting, more daring for the the future, proving a point, however negative that point is, a point that will outlast us.