May I expand on some of these ideas
Sorry if I'm making a noob of myself as I'm a new player to 7dtd. I actually sat down and started actively listing things I wondered why they weren't in the game myself, many of them are on here in short.
Sleeping got me right away, you'd need to sleep or you would sucome to disease, mental instability, or illness much more quickly. Sleep or lack there of should effect the pc with upper like coffee or speed to give mental focus, or melatonin to aid in sleeping if the pc feels safe enough.
Example of being tired could be falling asleep like micro napping on horde night, see a zombie and be shooting it then your screen goes black for a second and it's attacking you instead as a consequence of lack of sleep. Also power napping for like 20 in game minutes... could lead zombies to you if you aren't careful. Things like that, I don't know how hard that would be to code but I could see it functioning like the hunger/thirst/temperature systems.
Being able to make rope from plant fibers to make snares to catch small animals (rabbits, chickens, pigs) or a zombie snare trap or rope net trap, make placable/retractable rope ladders (something you can throw down off a wall or hole and climb down and leave it hanging till you climb back up with a retrieve option that could look like a coil of rope piled on the ground), rope foot bridge...that sort of thing.
Generators, made from the small engine and gas/bio fuel. You could have electricity for lights, cooking, water filter, and defense. Generators also make noise, but an electrified fence would be a good detourant for would be invaders, along with jumper cables to hook to a battery to electrify doors and windows. There is still a lot that could be done with existing items in the game. I wish I knew coding, I'd volunteer because I like the challenge of making things work. Oh yeah, why can't you construct a simple water purifier out of dirt, sand, coal, and cloth in a jar maybe, or it could be a new option from the new still/brewing stand after alpha 15.
Just some thoughts I wanted to put out there, or expand on....Hopefully this is the right place to post them. Thanks for sharing and letting me share too.