I agree with the trusts being better than squadron. We didn't have the scions going with us in the earlier dungeons though and adding them to those dungeons would be a little odd personally. The low level dungeons are for lower level content, when people are usually much newer. The squadron kind of eels like you're with a bunch of new people, though it does need some rework (Like being able to have them ignore enemies you put the ignore marker on and such)
Eureka just had the relic shoehorned on in, and the playerbase was really split on it. It got somewhat better in the later areas, but it wasn't enough to make me like it. You had to focus on ONLY your relic stuff and nothing else in there, so it's forced content for people that wanted a relic. It felt like FFXI 2.0, which many people didn't want, by a percentage of the community enjoyed enough to make discords dedicated to it. It didn't reach out to as many people as they had hoped though most likely.
Bozja was handled much better though, and they even added in the echo for when the instance is small, same for the bigger duties there so even small parties can handle it. They even made it an area to LEVEL UP FROM 71 UNTIL 80. Since they couldn't fit in a 5.X version of PotD/HoH that was incorporated well enough so don't say 'nobody wants them and nobody asked for them', that's just acting like your opinion is fact.
Would have liked a Deep Dungeon for 5.X but with covid terrorizing the world it's understandable that their own plans were greatly delayed, with some even being scrapped. Glad it was semi added to Bozja for people leveling so they could better multi-task/make use of their time. Maybe we'll get a new one for 6.X, fingers crossed
Monster Hunting is basically the Hunt Marks now. You can get daily/weekly currency from them and some EXP as well. Making it one time for each class again feels kind of pale in comparison. It needs some re-working though for older content personally...
Restoration needed instances.
Blue Mage isn't really 'old and forgotten'. They get 1-2 content boost per expansion, and they can usually be used in some more recent content (Like doing into old instances for relic parts and the like). I would like some more unique stuff compared to the Masked Carnivale though. The fact it's 'do this fight one exact way or lose' kind of feels meh. More so when you have some personal issues, like I go into sensory overload fast, needed a friend in call with me to call out certain things for me or I couldn't do one of the fights.
Levequests were decent-ish to help new players learn about some mechanics, but some were just thrown out/never used in some content. Like only time we ever had to 'lower enemy HP to X%' is when catching them for a sidequest or the like. They could have been expanded a bit more.
Glamour is what it is right now, and I think it's safe to assume unless they state they're doing something to it during an expansion drop, they won't really be doing anything much with it.
Also you can't learn what direction to go from just sticking to the same ol' same ol' and new ideas are needed to see what the playerbase likes. If they stopped adding new features, I think the game would get stale.