I think the writing in general isn't what people are mad about as far as the story itself may be, but more so the departure of how amazing the character writing and direction was in Shadowbringer and Endwalker and more-so than the writing itself it's the fact that XIV's questing (the way you NAVIGATE) the MSQ in general is severely outdated and there's no pull from a foundation of mystery and resolve which Shadowbringers and Endwalker had pushing you through some of the poorly paced. XIV has always had insanely poorly paced parts in all of its expansions but this is at the forefront because you have nothing to chew on while you go through it which is inevitable to happen but at the same time you have to contend with what XIV has always have been and that's a poorly disguised VN for 90% of its runtime.
I see some people saying "Well if they get invested into the story and not feel the urge to skip some stuff maybe they'll appreciate X/Y/Z" but you can't really blame people for being disconnected when they've had several hours of doing outdated quest design and reading text as their reward. I have no issue with the text itself, I quite like it myself but you need to give people something between these.
Tell me if you've heard this story before:
Mr. Questgiver sends you out to find a single Thingamajig.
There are 3 spots you can look at, or maybe even talk to 3 people who know about the Thingamajig.
You search these 3 spots/talk to these 3 people and it's no where to be found, however suddenly out of nowhere on the map sparks up a location where the Thingamajig is, you'll likely have some text, you might be lucky to fight a mob that dies in 5 seconds or you will be greeted with a cutscene, if you're lucky it might be voiced and properly cinamatic.
This is basically 90% of the quest design in XIV, you might also follow someone twice or thrice through the MSQ, rarely you might even use the 'aiming quest' to spot stuff and once in a blue moon you'll get a solo duty.
You can't really grab someone's attention when you're giving them mundane tasks constantly.
Another fact that might be jarring to some people is the length.
Shadowbringers was around a 30+ hour MSQ, it was nice and tight. It had two very badly paced sections but what expansion doesn't?
Endwalker was around a 50+ hour MSQ, a bit long, many cutscenes but it's expected because it tries to conclude a storyline.
Dawntrail is the same length as Endwalker which makes me wonder if some sections were cut down a perhaps leaving side+ quests to let people chew into it more if they wanted perhaps it wouldn't feel so badly paced.
I enjoyed Dawntrail personally but I really can't fault anyone for not enjoying it, it was way too long for it was and it highlighted how terrible the quest design is in general and the hoops players need to get to the meaty parts.