The Singularity Reactor was epic the first time.
The Aetherochemical Research Facility was epic the first time.
The Praetorium was... pretty ok the first time.
This game is really good if you don't repeat it much.

Can I get a reason to revisit story locations?
Weekly expedition to Amdapor to recover artefacts.
Daily Halatali score attack challenge against Flames' finest and captive beasts.
Just to spitball some examples.

I'd trade away 80% of the instances if the ones that remained had replay value.
Note some RNG is needed for replay value, can't be exactly the same run every time.
ARF was epic the first time, but how happy are you on the 37th time roulette brings it up? Pull that mob, take a left, stop at the wall, etc. You know how it goes, you've learned it, you play it like working at a production line now. No variation. Ditto for trials, you know how the phases go, you pre-position for the thing you know is about to happen, excepting some minor rng for things like which player gets a target marker.

You've seen this movie, you don't need to still be here. It bribed you back with tomestones or exp. What are past raids worth when they are no longer part of the current tier item level progression? They had a nice story at least and were epic the first time. How many new players want to farm Weeping City or Deltascape V3.0 now, long past their windows of relevancy? There's a giant amount of content in this game but like 97% of it isn't made to last. I think that's what people mean when they complain. They don't have unrealistic expectations about content production, just want a game design philosophy that gets more mileage out of the assets we already have. For every highly repeatable randomised PotD, there's dozens of scripted linear duties that are only great once ever and made with a single player adventure sort of design mentality.