Lack of staple RPG tactical elements. This isn't just limited to MMOs. Things like elemental resistances and weaknesses and Physical damage type resistances and weaknesses, which could effect how you would gear for an upcoming piece of content. I mean seriously fire spells do as much damage to a magical entity of living flame as it does to a doll made of paper.

The game literally tells you exactly where to go for every quest objective outside of a handful of quests they intentionally designed to not fully track in the quest tracker. Most the time you don't even need to bother reading the quest dialogue. You can just open log and click button to see where the next marker is. At this point you can just disable your brain because its no longer needed.

Outside of a small handful of attacks every AoE is telegraphed long before it actually happens. Add to it content outside of savage raids and trials or ultimate with a handful of exceptions isn't really punishing to the people that get hit by it. Add to it a non existent penalty for dying and we now have little incentive for people to actually learn a fight because its not needed for progress. Additionally they nerfed content making it even easier just because people didn't want to learn how to do it right and weren't happy they couldn't just die 5 minutes into the duty and wait for the other 7 people to clear it for them.

The secondary stats for the most part have so little influence on a build that a majority of the time it has no actual effect on gameplay or performance. They could rework this to make things like skill/spell speed, tenacity, and piety be far more impactful to the actual game. Then maybe we'd see melds other than DH, crit, det on everything by people that want that extra 1% hypothetical DPS output they'll probably never achieve because they haven't developed their player skill to a level that it will actually matter.

4man duties are far too linear and basic in general. Visually they are quite well done. However from a gameplay standpoint they pretty much feel like 1 straight line with occasional doors or barriers keeping you from trying to sprint to point B while ignoring everything. IMO many of the duties in ARR are far better designed from a gameplay prospective than the ones that came out from HW and on. They need to drop the slot car race track design then throw in more instances of interesting dungeon mechanics. Add to that the only Raids that felt like actual raids to me were the ARR ones for the coils of bahamut. The ones afterwards just feel like having a second set of trials.

I'm a bit of a connesurier of MMO's Having played numerous both free and paid over the span of about 25 years. I've been gaming in general for close to 40. Games in general have been getting easier and that decline really started when companies started pandering to noisy minorities of their playerbase that wouldn't stop crying on the internet.