As someone that started back in the 3.x cycle, and is basically only just caught up to where the game was when I started, I can say there's tons to do if you actually pace yourself. Granted, most of it is a grind, a dreadful one at that. But if you want to be completionist...

That said, when only a certain subset of the content is what appeals to you, naturally very little of any patch/expansion will keep your attention.

Perhaps it can be said the game caters best to the completionists. I'm wrapping up getting combat jobs to 60, but I've still got to loop back around and get my crafting and collecting classes up (finishing off those Moogle tribe quests in the process), I'm working on a second ARR relic weapon (and regretting the decision every step of the way), while starting a HW relic (regret soon to follow). I've almost finished off the ARR sightseeing log. I could craft one of everything just to say I did (damned addictive checkmarks). I think I've still got a set of ARR mastercraft books to get (stupid demimateria requirement). Demimateria! My desynth skills are woefully low. I was abandoned in an FC, I could figure out these exploratory missions. I've been to the Diadem once, that was kinda neat. I've heard there's a special zone I can see from treasure maps?

I've barely even touched PotD! The fact that I can't even get around to that astonishes me. It just comes off as the thing you grind so you can skip all that other stuff and get straight to the small slice of content you think you want. And if you have to do that, then, well, I hope you're getting your money's worth.