Sorry I forgot to reply to this.

Its hard to nail down specifics with general awful parts but I have a few notes on why some things get to be a little janky:

• Many mechanics/systems in survival crafting games have to work in all scenarios. Because of this, you can't (usually) be 100% certain its always going to happen as intended.

...For example, let's say you have a treasure chest, and when the player interacts with it, the game plays a fancy animation of the character opening and while the inventory screen fades in. But as these chests get placed around the world, you can't guarantee they'll always be reachable, at the right angle, or the player doing something dumb (like standing on it while opening it)

Now those are all 'solvable' but it starts to become a 'just optimize the production' in Factorio style problem where you're chasing edge cases. Even then, players will find new ways to break foolproof designs.

The general solution is just 'keep it simple' where box pops open (or just makes a sound) and a UI pops up. Not great... And sometimes kind of sucks.

• Secondly, many of these games are online/multiplayer. This normally shouldn't be a huge deal but networking has a few quirks that tend to show up. For example, networking infamously doesn't like replicated physics. Games like Rocket League are actual magic on how they figured out how to make that work.

Anyways the end result is a lot of fairly static world objects, and when you do get physics, they tend to have a lot of potential jank involved if you're not hosting the server.

• Regarding UI, making a good UI is honestly a difficult and rare skillset. A lot of engines have some built-in tools (You most definitely have used an Unreal Engine Uniform Grid Panel at some point) that work out of the box but sometimes have quirks or design issues that crop up as games get more advanced.

Making it work for gamepads and KB/M, readable on big screens as well as SteamDecks, and do background tasks like asking the server what my character's inventory or whatever is tends to be a feat when it all works correctly.

• Open world (which many of these games are) means a lot of content which means a lot of work for sometimes diminishing results. I think it was a developer for Destiny(?) who once said you might work on an area for a month only for the player to fly through it with a Sparrow in like, ~2 seconds.
• A lot of survival crafting games tend to be early access. This is 'fine' but some very vocal players are ravenous and burn through years of content in a solid weekend and still want more. The Early access effect is easy to see in these games where some mechanics are not well thought out or abandoned in later updates because rather than reiterating on them, devs are pushed to move onto new content, so you end up with weirdo design decisions or new game directions or whatever.

You also have devs who perceive something as more popular or more true to their vision or whatever and neglect certain aspects while focusing on others.

• Basebuilding has quirks, and its name is navmeshes. AI has to navigate through buildings using a mapped out mesh, basically. When you handcraft a location for enemies, you can tell them to do specific things like jump handrails or step off this platform to fall behind this fenced area, etc. When players can freely build bases, you need the AI to account for a lot of ridiculous things the player might have done, like build massive dirt walls in Valheim, which causes the AI's logic to stumble.

This has a side effect too though as now your AI has to account for terrain/location/etc before considering to do things. (Unless you built two different AI logic sets for each enemy, which is oof) Such as, the player is in range, but is the player standing on something? Is the player crawling under a wall and stabbing at AI's shins? What if the player is somewhere the AI can't reach at all, do they run away or throw rocks or what?

End result is sometimes you see AI doing funky/janky things in unintended cases.

(There are more issues but this post has gotten a little too long as it is)

All of these issues contribute to jank feel and can actually be kind if difficult to solve, which is why many open world survival crafting games stumble here.

All this being said, I agree with you, the genre has a lot of jank and it gets ridiculous sometimes. I have a joke saying that its a design law for all survival crafting games to have some serious game-breaking quirk, and so each new one that comes out, its not about if its flawless or not, its if you can handle whatever inevitable serious quirk it does have.

I have played a lot of games in the genre and always hope one of them will eventually nail it but it hasn't quite happened yet.

I can't help but notice the generality statements like "I lament not being able to put into words exactly what I mean" and "why also copy the awful parts?".

Do you know "Chesterton's fence"? It's the metaphor that you walk across a meadow and come upon a fence that's in the way. That's bothersome for you from walking there, so you want it gone.

But, the lesson supposed to be that if you don't know why it's even there, you shouldn't remove it until you learn why. Might be that there are sheep there that need to be kept from running away or something like that, etc.