How would people feel about a bestiary?
Say you have an empty book, underneath hunting lug or wherever, called "Bestiary"
The first kill of an enemy simply labels it's name and shows a picture of it, and so on with varying degrees of optional rewards.
- 5 Kills: Unlock location data
- 15 Kills: Unlock loot drops, and percentages
- 50 Kills: Opens up a tidbit of lore on the creature
- 150 Kills: You unlock a title, say "Yarzon Slayer"
- 500 Kills: You unlock an acheivement and some vanity/exclusive gear for that creature, etc. a wolf skin you can wear
- 1000 Kills: You unlock a special, unique, completely optional item, say "Sun Bats will now come to your aid in battle, and no longer aggro you *on world map, not during treasure maps or quests"
- 5000 Kills: You unlock the full lore for that creature, a cutscene, the title "Researcher of Diremites", and possible a vanity weapon with a special effect such as always doing critical damage to that enemy type and raising its drop rates for gil and items
I think this could add incentive to kill world mobs for some people, a bit of grind for others, and I don't think it would be too hard to implement.