It is to be expected, but it is something I imagine you should design your whole game around since it is a subscription-ending problem. Like, fixing nothing else, I think it would have made more sense to take all those optional dungeons and put them at 45+. If you wanted to make a game which pushes players to cap in a short amount of time, then that's where you should put the content.
Naturally, I don't think that's a good fix at all and think the path to cap should be longer (and enjoyable to repeat). Having every quest have a decent chance of a failure (but low costs for failure) is probably a better way to do it. In beta phase 3, doing the lv. 15 main scenario battle took a lot longer for most and it was a lot more satisfying and memorable. (On release, I did it butt-ass naked and cleared it without really trying.) Add some better hints for weaker players, as they did. Win, win. That would mean more encounters like Titan and Garuda, content everyone is going to have to do anyway. Why not make the quests after Titan somewhat stimulating? FATEs could be tougher. Guildleves. Even dungeons, which don't quite cut it for most of the game (although they are comparatively much better than most content in the game). I will never comprehend why AF quests are so easy when they make much gear in the game invalid. Also because leveling is such a speedy affair which hands out perfectly usable crafted gear like candy, there is no real reason for you to attempt to gear up classes before cap (would have said around 45, but AF quests take care of that).
Then the endgame was designed in a way where you can only have so many valid activities at any given moment. The stats/progression doesn't allow for much side-grades (the closest thing to sidegrades would be crafted gear, but that's based on tomestones... as is non-crafted gear). That's what chasing item level and nothing else does. Looking up, you see gear checks you can't clear. Looking down, you see content with rewards that is useless to you. If you are going to go this route, I assume you'd do better than something add such brutal walls to grind over. I don't think people will stick around for this. Moreover, I don't think there will be community to make it bearable.