Railings for stairs
Ability to build into water (i.e. build steps into water)
"Craft all available" option for crude rope, bug rubber, etc...
Clothing and character customization at the beginning of the game (I understand the game has a storyline, but we never see any artifacts that show photos of the children so it would be nice to be able to choose what we look like)
My team is having issues with inventory and trait retention; there have been several occasions where they've loaded in and all of their character work/inventory is erased, so I had to load an earlier save file to fix the issue
Archways! Doors can get cumbersome so open/close inside the base and leaving the area blank is not aesthetically pleasing
Ladders; stairs take up so much space when you're trying to build upwards and having to put trampolines every 3 floors wastes resources
More ability to build 'into' things; its random how you can build into certain things like rocks but then you can't build into juice boxes or whatever else