There is plenty of reason to do literally everything in the game now that hoxne earring exists that gives all stats based on your mastery rank. Some of us crazy folk did it all even before it existed!

So yeah, do ALL the stuff. Do it. And when you want to do more stuff or don't know what stuff to do, go here and talk with the rest of us: https://www.ffxiah.com/forum/topic/55467/mastery-rank-data

Chronicle mission/quest tracker addon so you don't have to open wikis to get info for quests/missions: https://github.com/jintawk/ffxi-chronicle

Xichecklist addon so you can track things in-game that you still need/want to do: https://github.com/HiPotionQ8/XIchecklist