One thing you really want in an MMO is varying content that is long-lived. Not a lot of the content in FFXIV is long-lived, and arbitrary time gates do not make something long-lived. It just makes it to where you have to wait a week to play the game for an hour or two.
Long-lived doesn't necessarily mean it has to be hard either. Not all content needs to have a static group and a month of practice. It just needs to have a reason to keep doing it beyond the first week of a patch. A reason that goes beyond it being "fun." Fun is only one aspect of it, and a grind does help at times. There's a fine line between a grueling grind and a fun grind though.
Based off of recent content:
8-man Raid Normal. Takes about 1-2 hour(s) per week. Only long-lived because you have to wait a week to get gear again. Fun, but not worth doing beyond getting the gear each week. By the time they allow you to lot more, the 24-man will be out and the gear is replaced.
8-man Raid Savage. Pretty much the same as above. I don't touch them during the cycle, but me doing them won't make them long-lived content.
Island Sanctuary is effectively done after 1-2 week(s) after the patch. Yes, they will add more to it, but is it long-lived? Not really, no. You can check on it every day, but it's pretty forgettable.
Variant Dungeons are probably the best thing I've seen added in awhile. I loved that I could duo it with a friend. Just finished this one though, a week after patch. Gear isn't really desirable enough to grind out. (Can't even wear the hat.) They said they'd add more later, but again, maybe 2-3 more weeks worth of content in an entire year.
Criterion Dungeons I don't really care about. Not gonna complain about them. I'm just not into savage type content. So for me, personally, it's untouched content that might as well not exist. However, it is content that will not live long for the majority of players.
The reason this becomes more and more of a problem, is because the time between patches keeps increasing. Four months now between major patches, and we get week long content sprinkled in here and there. Gear is replaced every two to four months. Hardly anything lasts beyond a week in a game where you could potentially log in every day. And their stance on it is "go play other games."
They either need to add new systems, or more reasons to do the newer content. As well as adding more reasons to possibly grind out old dead content, other than tomes or a roulette.