considering that this year alone i cleared both palace of the dead and heaven on high more than once in different groups simply because it a) still is fun to me and b) people in my fc/friendlist wanted to experience it pray tell why they should change it ? it still has use (going in solo for the challenge, farming it for mounts/to make money, leveling characters/just doing it because i can to waste some time because i feel like it), some of my fc mates are actually currently going through eureka for glamor so again, why does it need change ?
when i said "making it optional is NOT a fine line" i meant it. the fact that it is optional, absolutely not required but does in fact offer rewards people may or may not want makes it perfectly fine for the system not to evolve or you might aswell start complaining they don't evolve riichi mahjong even though its in the game.