While I have enjoyed ARK immensely, there have been issues with griefer tribes who like to maraud across maps, destroying other players structures. This has led me to think that having the ability to camouflage structures, at least in very specific instances, from detection. For example, Say you have an outpost, but have a griefer tribe or dangerous wildlife (like Carnotaurs) who can smash your building. One solution would be to implement the ability to build in large trees, which can have some snap points for ladders, or you can add a rope ladder w/ counterweight, which lowers when you interact with a hidden switch (like a nondescript rock), but otherwise functions like a ladder. furthermore, until such trees are available, a stopgap/alternative could be to include camouflage, which when applied to a pillar, makes it resemble a regular tree. This same material, when applied to the bottom of a ceiling piece, would reskin it to resemble swaying tree branches! Combined, you could have a treehouse that you could hide in a forest, undetectable to the casual eye unless someone chops away the camo by accident. ALso, someone suggested a Ghillie suit, but rather than a whole outfit, I think a skin can be applied over regular armor instead.
Also, I had thoughts on AI and farming, firstly, training your dinos to use a composting bin as a litterbox if nearby. This would streamline some of the fertilizer gathering that can be somewhat random. Another AI is to add 'fight or flight', where dinos, whether tame or not, will attempt to run away when their health drops to a certain point, but will turn and fight if their health drops below that to a 'desperation' level. Fortitude could make the threshold window decrease or disappear entirely. This has the added benefit of allowing your pets to defend themselves from wild carnivores when you logout. Finally, flying pets provide an interesting defense strategy if you can set their AI to patrol a certain radius, and upon encountering a hostile human intruder (performing a hostile act against the player, not simply passing through), will dive, pick them up, and drop them to their deaths.
Ziplines would be immensely helpful for covering large distances quickly, and provides an alternative for getting across canyons and down cliffs.
The building system could be a bit more forgiving, with some fine tuning buttons for placing on snap points, which can be challenging in odd camera angles. being able to rotate hatchframes and/or trapdoors can help with ladder alignment issues, preventing one from closing/opening a trapdoor when they descend/ascend. An alternative hatchframe piece allowing you to place a ladder on a pillar and climb upward through a trapdoor would be nice, like:
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Finally, when demolishing a structure, if connecting pieces are destroyed as well, such as a tall ladder, you should get a refund on the connecting parts as well, as well as a prompt when overwriting a piece so you don't waste precious resources placing the same ladder or pillar on top of itself.