The problem is that SE insists on releasing dungeons that are so ridiculously far behind the current iLevel curve that the playerbase has overgeared them before they even release. Even ST (On release) was basically undermined because Hunts invalidated it in terms of gear acquisition, now it's a bit better that the loot has been expanded but I still don't feel the need to run it at this point. In this game most encounters are balanced around the strength of your gear rather than the strength of your abilities, and the ability to avoid certain death mechanics. As long as you are able to survive instances of instant death, you basically win the encounter so long as your DPS is either good/overgeared enough to survive the enrage (Provided one even exists).
Rather than actually continue the dungeon/trial difficulty to exist as a sort of upward trend, they insist on continuing at this baby step pace (Especially with dungeons, their initial misstep with the item level of Ramuh EX and Moggle Mog EX also speaks to this). The reason that things like even Wanderer's Palace and Amdapor, Chimera and Hydra were initially difficult was because at the time the original 2.0 players were doing that content it was literally -impossible- to be overgeared for it, much like it was originally impossible for anyone to overgear for T9 when Second Coil was released. With the availability of easy i90, or even easy i100 at this point releasing dungeons with i70 or i80 loot is just a waste of time. It's literally a waste. Nobody wants to do content like that when even casual players can understand that hunts are a better use of their time which lead to better gear in the short-term. It also doesn't help that SE insists on flooding those dungeons with a bunch of crafting mats instead of gear, so even if you wanted it for vanity you have to struggle for it.
Most everything in 2.0 up to the completion of the Relic + Coil 1 = Very good progresson/balancing
First three EX primals + Leviathan EX = Very good balancing for the time in which they were released, rewards people wanted and challenge that was at the time appropriate
Moggle Mog EX and Initial Ramuh EX= Rewards too low for difficulty of the encounter, I personally don't think Ramuh especially is that bad but at the very least it's a fight with lots of individual responsibility
Every dungeon since 2.0 Amdapor with the exception of Speedflox = Totally ignored except for expert roulette at this point unless it's needed to unlock something at level 50