This is such a non-issue. The game is not heading in a "Dark Souls direction". The dungeon design/difficulty has remained pretty much the same since ARR. If you are running a dungeon for the first time, sure it is a challenge if you don't know what is coming and it's OK to wipe. You learn from your mistakes, try again, and you'll eventually clear the dungeon.

But I should point out - this is a Level 100 dungeon - not counting side content, there are 58 MSQ dungeons, 29 MSQ Trials and 3 MSQ Alliance Raids (Crystal Tower) all before this final Dungeon. Unless you used a skip from the Online Store to play Dawntrail, or have some disability that prevents you from playing properly/well, there is no excuse for not being able to clear a MSQ dungeon. This is quite literally the easiest battle content in the entire game.

If you are still struggling, here is a breakdown of boss mechanics for this dungeon this doesn't include Boss 3 in case you don't want to be spoiled.

Boss 1: Boss sits static in the north of the arena. It will do a large frontal cleave, which you can dodge by running to it's sides, as well as side cleaves, which you can dodge by running to it's front. Very simple. It then starts doing it's main mechanic: a "U" shape of telegraphed AOES. The Cross sign does line AOEs in a cross pattern, the Circle is a Dynamo/In mechanic. Again very simple. You watch the order they spawn and avoid the AOEs and run into the safe zones. It will then start combining this with the Front and Side cleaves - now you need to pay attention to the order of AOEs and where you need to dodge. Finally, a combination of Tankbuster/Stack and spread AOEs will also appear. All of this is stuff you will have done before in previous fights. Nothing here is new, just another application of the same mechanics. Now I haven't done this with Trusts, but if I were to, I would make sure not to blindly follow the NPCs.

Boss 2: This boss will "break itself apart" and use it's body to form a triangle in half the arena - stay out of this triangle. It will also do a middle line AOE or side AOEs based on the direction it is facing - just go into the opposite section depending on which one it is doing. Finally there are line AOEs from the north, with 1 or 2 columns that are safe, as well as Spread AOEs - make sure to stand in the safe column and spread appropriately. All very simple stuff. The difficulty comes from the combination of mechanics, however they are simple enough to understand and resolve without issue.

(Apologies if I missed mechanics, don't have the game open as I type this to check)

Overall, this dungeon is no more difficult than anything that has come before it. It seems to me that you have an unwillingness to learn which is hindering you from the playing the game. Dungeon design is fine, and does not need a difficulty setting - you should have the skillset by now clear this sort of content, and if you can't? Then perhaps you should play something else.