DT difficulty is where it should have been for Endwalker period. You've just never put in effort to actually learn how to play combat in FFXIV.

Nothing is new.(you've seen these mechanics before EVERY. SINGLE. EXPANSION)
Nothing is random(even the "random" aoes in some of the dungeons)
Nothing requires high reactions speed(The cues are VERY obvious and you have upwards of over 10seconds to solve the more layered mechanics which BTW are still things you've seen before)

If you're genuinely walled by a boss(wiping 10+ times with no progress) Ask for help because chances are you're missing something and solving things in a very inefficient way. If you're rejecting help just because "you know how to play. you've been playing since XXX expansion" I think the problem is obvious...
If you can react to a traffic light turning green before the old guy behind you honks, you can play this game just FINE.

The MSQ dungeons is something that EVERYONE interacts with for the WHOLE expansion, its not just a isolated event. You can't put in a "story mode" without having HUGE impacts on the whole state of the game e.g If trust become too strong exp would become unbalanced e.g2 If you have a story mode how would you do roulettes? two different queues? diluting a player base for no reason?.

The only way a "story mode" would work would be to remove all rewards and progression from that track and at that point... go watch a youtube video of the MSQ. Don't waste the devs time.

Stop calling yourself "casuals". Casual players can still beat ultimates, EXs and savages just at an extended time period. Trying to change the game because it doesn't meet your standards while calling out everyone for enjoying a more engaging piece of content is hypocritical.

To the people who have genuine reasons which impact their ability to play the game, I sympathize with you, no one genuinely flames people for not being able to perform during roulettes and most will carry you through it. Also there a multiple ways to make your setup more efficient and tailored to your situation but you also have to understand that this game can't be tailormade for every single individual.