I think a major problem is the gulf between normal difficulty content, and extreme/savage. Extreme difficulty is a sweet spot for many people. Harder than normal, but not the steep penalty for failure like savage. And yet, we only really get one of those EX trials every several months or whatever. Meanwhile, if you enjoy normal difficulty content, that's like 95% of the game, and if you enjoy savage+, there're 4 raids per tier and an ultimate for you to sink your teeth into. The midcore people get lost in the middle. I haven't done the new Criterion dungeons yet, so I can't say if it scratches that itch or not. A relic could tide people over who just want something to do, but the way it was implemented, you can be done with it in a single day. Maybe more if you're gearing multiple jobs, but yeah. And the dungeons you grind for tomes aren't exactly fun. The level 90 dungeons are really lackluster this time around; I don't even look forward to doing expert roulette anymore because troia's a boring dungeon with an add boss, and the other one is just old at this point.
Basically if you're the type of person who's bored by normal difficulty stuff but either can't get 8 people together for savage or you just aren't interested in the prog process of wiping for potentially weeks because of other people, you get 1 EX trial roughly every time a new tier comes out and that is it. And people sorta stop running it after the first week because of how the content rollouts work. For example, when Barb EX came out, a week later the new savage came out so everyone I knew stopped caring about barb EX and the PF quality plummeted. I might be off-base here but I think the game's making a mistake by not appealing to this middle of the road group. Maybe criterion dungeons will scratch that itch. idk. People have been asking for harder dungeons for years, but the way the devs phrased its implementation, it sounded like they wanted to just make even more shit for the savage raiding crowd, since it's tuned for savage bis. I genuinely wonder if there's even a place for mid-tier difficulty stuff in this game anymore.