I think that, if it ever becomes feasible to do, it would be a fantastic idea to have two versions each of the Darkwhisper (both Lower and Upper), Forgotten Payon, and Jawaii Ocean Island maps. The new "normal" version, where all the mobs are nerfed so that a player with unrefined/unruned/unhoned Osiris/Himmelmez/Eddga equipment can comfortably operate solo against normal mobs and a party of characters with similar gear can deal with the bosses (the quests, both story and daily, should be changed to be done on these versions of the maps), and the "hard" versions which are just the maps as they exist now with no modifications except that the quests have been moved to the normal versions. Maybe also make it so that the bosses in Jawaii Ocean Island Normal can't drop cards, but their respawn time (and the respawn time of the Forgotten Payon bosses for that matter) is reduced significantly to make them more available for the quests. The reason for not letting them drop cards is both so that the amount of their cards that exist doesn't suddenly skyrocket, and to dissuade from camping them so that their reduced spawn times aren't rendered moot. Maybe strip 60%+ Honing Polish drops from the Normal bosses too for similar reasons.
The reason I think this would be a great idea is because right now, a casual player has nothing to do after Osiris' Tomb. They can't solo the Darkwhisper because the monsters have spiked defense and higher offense, while in Forgotten Payon and Jawaii Ocean Island they have massively spiked offense on top of that (even a tanking class, if ill-prepared, will get oneshot in Jawaii Ocean Island). If they go into parties to level off of daily quests, they're still effectively just getting carried and will still get oneshot by boss AoEs if they try to do anything other than stand as far away as possible and not actually help. There's also the fact that this wouldn't require the creation of any new assets since it'd mostly just be a copy/paste job with adjusted numbers, so it'd be a fast way to recycle content without having to think too hard about it. If it turns out to be too easy, then there's no rush to fix it because that's better than being too hard, and if it's too hard then basically nothing has changed and we're still right where we started. After letting it simmer, the idea of adding some exclusive drops to the Hard versions could be toyed with, though what exactly those would be would require some discussion unless it were interpreted as stripping Honing Polishes (and maybe Seed Runes, though I'd personally say to leave the weapons/armor alone) from the Normal maps completely.
The second thing is that changing Forgotten Payon so that Dragon Tail or Eddga Jr. (not both, obviously) drops Priest/Monk armor instead of accessories would be fantastic and even easier to implement. That would be fantastic because those classes are at a really unfair disadvantage considering that Bamboo Panda is so much more powerful (thanks to its 400% damage self-buff and AoE) and sparse than the other non-boss mobs, and considering that using Eddga shoes and gloves instead of Serenia shoes and gloves is popular due to the latter set having a deficiency in Runeholes with those pieces, that's a problem that affects players even at the very end of the game.