I do wish that at least on the dungeon side they made the leveling dungeons scale a bit in difficulty as you get higher level, especially with how it felt like the first dungeon was a punch to the face in difficulty compared to what came before when starting a new expansion then they get significantly easier and then the last dungeon is another punch to the face in difficulty, during initial launch at least. I think they could scale that difficulty curve better to make all the leveling dungeons a bit more engaging.

In trials, I am a bit spoiled as a tank since I think the "challenge" in normal content and some EX content is figuring out what I can survive if I just eat the mechanic to continue DPSing the boss. Trial 1 in EW is pretty bad in that you can pretty much eat every mechanic that forces you out of melee range as a tank and have no issues clearing it.

In the MSQ I wish there was an option to make the duties have a hard mode akin to how there is an easy and "you can clear this difficulty while asleep" mode. I think the Garlean duty in EW was good as the timer made me feel rushed to complete it and the ambiguous directions made me have to figure it out while still beating the timer. It made you think about how to navigate to minimize combat since it was so easy to die and there felt like there were actual stakes with its placement in the story. Unfortunately almost all other MSQ content is designed for the absolute lowest common denominator to complete with relative ease for most of it and because of that there is no way for it to get more difficult or pose a challenge to a large portion of the playerbase.