Since a few people brought it up, if I had to criticize one other thing, it'd be the Abyss. Lightly, because it's optional, but it does deserve it. On softcore it's whatever. I like that there's a biome that makes water-related equipment useful, even if rarely, but it's somewhat muddied by the fact that it's glitchy to start, and what you REALLY need are the special Abyss equips.
Then the Abyss equips are a sprawl of different materials coming together like the Ankh shield, with some of the ingredients being things you normally would never want or need. It takes so long to put together for a region that offers extremely minimal benefits.
I'll play mediumcore sometimes, to deter the habit of recklessness, and I find myself completely avoiding the Abyss pretty much indefinitely. There's nothing there, and if you bump into a Mauler Shark it's instant death for most of the game. I think the Mauler Shark is probably my biggest gripe. It's got as much HP as the Leviathan, it explodes, and does more than three times the damage of the Leviathan. I don't know how the Scourge can survive in the Piss Ocean with apex predators like that in the water. Maulers would tear the Scourge to shreds. By the time you finally get down low enough to see Reaper Sharks in the late game, Reapers are only just barely tougher. Why are Maulers so strong? Their existence makes it safer to tunnel sideways into the Abyss from the caverns.
It's not a "miniboss" if it could kill the Moonlord.
I think the only time Piss Ocean is useful to the player is just after you get a shadow key, because the weapons in the chests are useful then, and the tool to control rain is handy. After Wall of Flesh, you'll quickly upgrade past those items. You may be able to fish up Abyss crates post hardmore, but it's all pre-hardmode tier - and think about this: if I'm fishing for crates anyway, the crates will provide me with titanium and adamantium, so why would I ever want to see those lower tier weapons by fishing at that stage of the game?
It's really all for its own sake. Some people say the Abyss is "scary", but I half feel like they only say that because they know they're supposed to think it's scary.
There was one fun side-effect of the Abyss, though. I dug a long tunnel through the caverns and ran rail across it, and the rail passed over the dungeon. Busting a hole in the wall of the Abyss caused water to flow out of it and endlessly down into the dungeon. By the time I'd realized what I'd done, the whole place was flooded, which meant there was one stupid place I didn't want to be where my water equips where useful, and one place with a lot of important things in it that was almost totally underwater. Accidentally made water equips super useful!