Very few games are perfect on release, in some ways Diablo 3 was the same, POE probably wasn't anything like the current iteration of POE either.
Diablo 4 doesn't feel like it's completely lacking or released too early, but I think it's more that some stuff just feels unrewarding.
For example those whisper caches. I was only doing them when the dungeon was also one I hadn't done before, there is no sense to run them as the caches are awful otherwise if not getting a side-benefit of the renown/aspect unlock.
In some of the dungeons at the mid-point you would get a mini-event that could spawn traps to undo, or elites to fight. I had one earlier that had like 8 elites in it. Problem is they don't drop any loot in this mini-event. Why am I killing them for no loot or rewards?
For dungeons, it's same old thing each time, the random layouts aren't that interesting, and you have the same missions over and over, kill these elites, free these prisoners, kill these blob things etc.
I miss rifts a little where it's just kill enemies and then fight a boss. Though I do sort of get why they've tried to move away from these, as in D3 at endgame you would just run rifts and never leave town, they want people out in the world doing stuff, but once you've unlocked the renown for all the areas, the world stuff isn't as interesting anymore.
I actually quite liked the helltides to a point as well, those mystery chests were good, and it as a good way of combining events for obols + helltide rewards in one 20-30 min thing, but the density of helltides can feel a little weak so you're hunting down small packs of enemies. I'd like to see more hell from the hell tides I guess where you're wading through hordes of enemies.