Things I dislike:
Books, just because each relic required too many of them.
Light grinds, because they feel so random. Sometimes duties give brilliant light, sometimes feeble. Changes every few hours and just overall promotes grinding the same instance over and over.
Drops that are not guaranteed. On release, you wouldn't always be guaranteed drops from ARR dungeons, requiring players to do them an unknown amount of times. Relying on luck and RNG is not enjoyable after beating the same dungeon 4+ times.
Desynthesis and crafting required. Most of this is unnecessary now, outside of ARR relics.

I think I'm fine with everything else. Things I love, though:
Bozja is number one, as I legitimately enjoy FATEs in highly populated areas. They feel alive. The boss fights in Bozja are especially enjoyable. I like Eureka too, but it was not nearly as enjoyable on release- especially not Pagos.
I like when I have to do daily quests for rewards, like for 50/60/70/80 Roulette and/or Leveling Roulette. I love dungeons but the lack of high rewards for them make it so I do not do them as often as I do other Roulettes.