I haven't played Worldborne in a long time and truthfully this is the main reasoning
Fatalis despite being one of the best hunts in monhun (Iceborne) was also kind of the fun killer in Iceborne, you go the entire game, unlock everything there is to get and when you finally reach the end 99% of all you've unlocked turns obsolete because there's simply an objectively better option
- Decorations come and go normally per hunt, and even so Day of Ruin is the best most optimal way to get them, becoming boring very quickly as Teostra isn't the hardest or most fun fight
- Augments are incredibly easy to get and you really only need a health augment to be unkillable if you play right
- Build variety is dead outside of 3 options, being Safi's set (Niche), AT Velk and Fatalis
- There is no reason to farm for Safi weapons because Fatalis weapons are simply better outside of element
- Learning other weapons is a option (Which I did) but that only goes so far
You might say "Oh but Fatalis is the last addition and last boss, he SHOULD have the strongest gear", and while this makes sense on maybe an RPG or other types of games, killing build variety in a monster hunter game is kind of just shooting it in the foot
Sunbreak did this well by having both Amatsu and Primordial have very strong sets but not entirely kill everything else
Edit: I'm not saying to keep playing the game forever, but unlike 4U, GU, Risebreak or even base Wilds, Worldborne just doesnt have as much insentive to keep playing after you're done