This is one of the many reasons Item Level gearing in MMOs is terrible. It creates a situation where the developers need to either horrifically limit/lockout content (Like Coil, CT, and Myth caps), or pump out content that upgrades your I.lv faster than can be reasonable.
FFXIV is designed in a way that nothing matters but the I.lv of your gear, making it difficult to give any of the top tier players reasons to play in situations like this. This is a bad thing. Theres nothing they can do to change it at this point as the MMO is released, I just wish they fine-tuned FFXI's gearing a bit more rather than just go with the generic modern MMO I.lv scale. While FFXI did a lot of things wrong with its gear, it opened up a true RPG feel to it.
Even now since FFXI has adopted a god awful gamekilling Item level scale, it still acknowledges that the sidegrade/unique item system works, and even with the Item-Level scale, there are still cases where an Item Lvl 119 is beat by a 115 due to additional stats. It creates a situation or instance where lower level Item level gear can be useful to a higher item level player, which is something SE could learn from their other MMO
Until then, we deal with the reality that Item level is end-all be-all and that any content without an increased Item Level becomes useless to the most devoted players, and losing them does not spell good business for this game in 1 or 2 years. But I know asking some of you to think about the future of this game instead of your head rushing with high levels of whiteknightery at the mere thought of all them filthy hardcores being so ungrateful and asking for things like relevant content is a moot point... But you can try right?
I know when someone brings up FFXI's gearing every babbling mutthead has to come in and make a joke about "Resist Poison"+1 or gear swapping. But I know reading is hard, but you can see above the word "Fine-Tuned", which means, "Improve and flesh out more" in so many words. The idea is i wish they worked out some of the kinks/negatives with XI's system and improve it into a functional awesome system, instead of just going "Sh*t we got to meet a deadline but we haven't worked on gear, Throw in generic Item Level bullsh*t and call it a day, should take like a week to program tops"