There are quite a few semi-exploity mechanics that are frequently employed, as well as mods that are frequently used to get around some of the game's shortcomings. I'm assembling a short list of suggestions here around these:
* Increased speed: Especially late game, projects can take a substantial amount of time to complete. It would be nice if we either had some way to ramp up speed either via the ingame controls or perhaps some research device like a... temporal jumpinator(?) that could act as a way to pass time quickly.
* Pipe snipping: I've seen a lot of streamers make use of the pipe snipping mod to help with pipe management as they work on their base designs. I feel like this tool could be made baseline
* Indestructible decor: Is there a reason we can't destroy this stuff? I know it's been a request in a number of threads, but I'd love to get feedback as to why this hasn't been implemented. Just tied to old code perhaps?
"Missing" In-game Systems
* Natural tile generation (to displace the metal door destruction trick): Voles kind of count, but they're so hard to manage. It seems like something simple like a tile depositor or even a shovel tool could be used to be able to fill in tiles with dirt or mud (or other soft material). I think that dupes should be able to plant in these as well, and you can balance the reduced plant requirements by perhaps further reducing plant output when it's dupe planted.
* Magma management: The current method operates around using pitcher pumps to dispose of magma, but this feels hacky. A better way might be to create a pump out of niobium and pump the stuff out, but currently there's no real way to get dupes into the magma to do the task. Maybe a niobium magma suit or a niobium robot that can be sent to do tasks in places where dupes can't get to?
* The Powered Airlock Switch: Many end-game builds revolve around using metal powered airlocks and automation to act as a sort of thermal switch, which again feels kind of hacky. Most of these revolve around thermal management of substances that can't be handled by in-game machines, like magma, liquid hydrogen/oxygen, etc. I guess I feel like if you've got an in-game device that uses a substance, there needs to be a way to process to that substance, even if it requires exotic materials to craft.
* I feel like it could be a bit more clear how pipe bridges are used to shape the flow of liquids/gasses, as the behind-the-scenes behavior of them isn't immediately obvious. Maybe a tooltip or tutorial?