Keep in mind that most of the players are the midcore crowd, so 1% players who grind their super duper raids that are 1% of content don't count!
#01 - Easy Encounters
You don't have to position the boss anymore. The boss will always move to the center of the arena. The boss will have a long, 10 second cast of a raidwide (it will never kill you). The hitbox is too big to cater to melee.
#02 - Easy, homogenized job rotations
Tanks play the exact same, with the exception of Gunbreaker to an extent. Hardly any class identity, PLD, WAR and DRK will press their shiney button and spam their big attack 3 times. Healers are the worst, just 1, 2 dps buttons at most while the rest of the kit is healing abilities you barely use. Every job, including DPS got their identity killed in both Shadowbringers and Endwalker. In Dawntrail all they got was a button that turns into another button. Very uncreative from Square Enix's part.
#03 - Burst condensed into a 2 minute rotation
One of Square Enix's worst mistakes was alligned every job to have a burst at the 2 minute mark. It's lazy, it's not exciting. I don't my favorite job to cater around other people's burst. Not everyone cares about savage raiding and having their coloured numbers displayed in a third party website. A good example of this is Black Mage who got much, much worse with the Ley Lines change in Endwalker, and not to mention all the buffs happening at the 120th second mark. Lazy design.
#04 - Removal of mob EXP / quick kill rewards
Back then you'd be rewarded for killing as much enemies as you can in a short time, as you'd get a bonus EXP reward the better you performed in a dungeon. But SE took that away. No reward for playing well.
#05 - Boring, linear and predictable dungeons
Everything is a long hall/corridor with no alternative parts, nothing interesting ever. We keep getting the same old dungeon that's a flashback about a civilization collapsing or going through the apocalypse, not original.
#06 - Less content
Back in Stormblood the patches didn't take as long to drop, we had deep dungeons, we had Field Operations, we had challenging Alliance Raids and we had more dungeons in the Expert roulette. (Apparently, way more in Heavensward and A Realm Reborn!). And please don't talk about Variant Dungeons because let's be frank, nobody grinds it outside of a few times. Not exactly repeatable content one does *casually*.
#07 - Club Advertisements
Many are sick and tired of seeing the Party Finder filled to the brim with +18 clubs ran by ugly modbeasts who on their spare time stay in Ul'dah Balmung congesting the server with their /beesknees emote, or worse yet, emoteing on top of one another doing things in public I dare not even mention.
Continues...