Warning: this does not contain story spoiler but does contain some details of the lvl 50 Job quest mechanic.
and now back on topic....
Having played through some of the lvl 50 Job quest, and watched videos of the other ones I have not complete yet, I would like to see more unique lvl 50 Job Quests for the upcoming 2nd jobs and Jobs for upcoming classes. Maybe add a 2 phase boss being in phase 1 you fight the current boss and after you defeat that boss a new boss will appear after a cutscene but the mechanics of the fight has change and you have allies, or more allies, or given a buff (story wise) to help deal with the sudden 2nd boss with entirely new mechanics and phases.
Most unique lvl 50 Job quests in this FF14 so far are
Paladin lvl 50 Job quest being very detailed in story, having 2 parts for the instance with different mechanic fights and testing your ability to work as a team with others. It even has that oh ***** moment in phase 2 of the quest.
Scholar lvl 50 Job quest is unique because it doesn't keep you in 1 location but serve as a test to see if you can keep up with your allies. The Instance for this quest is designed to be a mini-dungeon as well so you're being tested in your ability to handle dungeons as a healer.
The other Job quest are reletively simple and doesn't give the feeling I would expect for a epic final showdown moment.
Monk, Warrior, and Dragoon are mostly the same for their lvl 50 quest because they have you going through the basic 1 vs 1 boss battle you experience countless times already with the same old avoid this and attack that mechanics.
White Mage is simply spam heal to win while trying to perform DD at the same time.
Black Mage and Summoner is the same as the Monk, Warrior, and Dragoon but the boss fight is just with allies NPCs like past quest before lvl 50.
So what would you like to see for the future 2nd Job lvl 50 quests?