XI was not a casual mmo, it was a mmo where you got what you put into it. If you only played a few hours a week or 5-8hrs on the weekend you progressed at a snails pace. But you had the option to play for 50+hrs a week and never get bored as well there was literally that much to do in that game that progressed you endgame wise.

The content issue in mmos is caused by the casual focus. Devs simply cannot create enough content to keep the non-casuals occupied in a game focusing on the casual playerbase. Example FFXIV would be great for all players in its current design... if the devs released literally 15xs the content every patch (Not financially feasible, and honestly the 15xs mark is not that much of an exaggeration of what it would take).

It all comes down to design.

In XI and older mmos, builds were situational, gear was specific for certain things, leveling was slower... no BIS piece for everything. The lvl caps were not constantly risen. There for Endgame content built on itself. in FFXI for example Rise of Ziltart was equally as valid endgame wise as Chain of Promathia, which was equally as valid as Treasures, ect... Each of these also added lower level zones for leveling as well, the expansions expanded the whole game... the never replaced the content before it. This only broke down with the release of abysea.

FFXIV would had absurd amounts of content if everything from release of ARR was still equally as valid endgame wise. Meaning Coil 1-5 gear was still equally good in certain situations as stuff from Neo Exdeath. If stuff from Garuda was still as good as the weapon you get from killing ultimate savage bahamut. Of course the game is not designed this way at all nor will it ever be.

FFXIV is a themepark modeled after WoW... these problem will always exist. The flip side is casuals get more enjoyment out of this design.

In the end FFXIV is not meant to be a main mmo played longterm for 20 to 40+ hrs a week. It is sorta a side mmo you play with other games.