I can only play around 3ish hours max a day if I'm lucky, so to me there's plenty of end game content to do, stuff to clear, and my roulettes alone take half of that time availability. However I can see it being an issue for people with more time to dedicate to the game, or to people with a very specific set goal in mind.
Sadly it's difficult to proper balance those things, at least to me, because you might end up with a situation in which people with less time to play may never catch up to people that can play six hours a day every day. I do agree with some things you pointed out though.
And before someone drops the hardcore vs casual player card, people can be casual and play plenty as well as being hardcore and playing just a couple hours every day.
To me it just feels like people with a little bit more time to dedicate to XIV tend to run out of things they like to do faster, but Yoshi mentioned a lot of times that he wants this game to be a "no full commitment to X hours a day" kind of game.