In the end, MMO players want more variety..
Wrong in the end MMO players want more streamlined efficient content. That's why there's speed-running which avoids 60% of the dungeons 'content' because in the end it's just repetitive and the rewards are clearer for obtaining a better reward in the littlest time possible. This may or may not be fixed with how mobs will now drop gil... but knowing the playerbase, I assume there'll be a go-to instance that combines the best rewards in the least amount of time possible.

That's your true end-game, it's efficiency, not variety.