I don't think the problem is 100% not enough Endgame content, its all the gated progress that makes Endgame content a "Once a week" Thing. I mean Having only 2-3 Things to do when you hit 50 that actually involves progressing your character is a bit of a pickle, But not exactly unusual for a new MMO.
Come Monday, You get your 300 Tomes in a matter of a couple hours, and come Tuesday you do Coil and... Now you wait a week for it to reset. Its silly. With so little endgame content, gating it to a once a week deal is essentially banking on your customers not caring that they're paying for 8 hours of content a week. yes i know theres other things to do but when you release a game with content blocks such as this (Especially Myth tomes which horrifically gate your ability to gear multiple jobs well) you can't just assume every subscriber is going to pick up Crafting (Which is a pointless waste of time atm) or Gathering (Real boring...).
I tried leveling a second job to fill in the spare time but I got bored to almost falling asleep doing FATE grinding, I spent more time browsing the internet due to being bored to tears. I know the game is new, and i understand that theres got to be content restrictions otherwise instead of people complaining about only being able to meaningfully progress once a week (Coil/Myths), they'll complain they're capped on gear from that... Cause you know darn well some people will live in this game just to cap out on that gear if it was unrestricted.
Its a messy thing to do, But personally I think how they handled it is poor. Coil should be at best like Old FFXI Dynamis, once every 72 hours... Myth tomes should be at least 500 a Week (So maybe you can actually buy something once a week... 1 piece of armor a week isn't going to destroy the game, no?).
they could also make it to where we could exchange old Darklight for Half their worth in tomes, or at least break them down into TIV Materia, since they're completely worthless otherwise once you upgrade to Relic...
*sigh*, It may appear like i dislike FFXIV, but I really don't. I just think a lot of their limits, while necessary for an MMO, were just not well thought out... It feels like they copy > Pasted restrictions from other MMOs, but forgot a key aspect of this game. Job Changing. With job changing and these kind of limits, It almost pigeonholes you to one job anyway because of all the walls, gearing up 2 jobs is near impossible (unless in Darklight alone, which while not bad, Is pretty awful compared to the next tier, Relic).
FFXIV Has a ways to go, and personally I'd say wait a year to see how the game has come along, but unfortunately with the "Item level" Moto, in a years time you'll be so obsolete no one will want to help you... So this game is burying itself, like all Item Level MMOs do... No Content to start so people unsubscribe for a bit, and if they subscribe back they're now useless and no ones running old content to catch them up anymore. Its a vicious cycle and why most "Item Level" MMOs fail and go F2P.