As a player - who normally plays singleplayer - I want to point out that while all of this crafting stuff seems interesting to me, I don't think it's the area of the game that I would prioritize the most. I say this because when I play Project Zomboid, an improved crafting system is not the first thing that comes to mind, like: Oh! I wish the crafting system was better..., it's what the game needs!!
There are other things that I think would add more value.
Here are some examples that come to my mind right now:
1. Character animations and how they interact with their environment:
I think the characters should interact with their environment in a more visual way. Minecraft is a very inspiring game, but there's another one called The Sims, from which good ideas can be drawn. Beds, chairs, showers, etc. could do more than just decorate the scenery. After all, Project Zomboid has a lot of life simulator in it, even in a post-apocalyptic world.
I am aware of the work involved, and I wouldn't expect an indie company to reach the level of detail in "The Sims,"but any improvement in that area will be accompanied by a higher level of immersion.
2. Missions, secondary objectives, aspirations:
One of the strong points of Project Zomboid, which makes it very fun, especially when starting a new game, is the need to explore in search of weapons, food, tools, and everything necessary to stay alive. However, as days and weeks go by, one settles down, accumulates reserves, practices agriculture, etc. There comes a time when there is practically no need to move and the game becomes somewhat routine. One solves it by grabbing the shotgun on a Sunday to take a walk with the zombies. And I suppose that's what we would all do in a boring world full of zombies.
But I've thought, what if I were a doctor? Wouldn't I perhaps try to investigate the disease, discover its possible origin, cure, etc.? I would look for clues, samples, instruments like a microscope, perform biopsies, search for findings by other researchers, etc.
If at the time of creating the character, there were not only traits to choose from but also aspirations or missions, the game could become more interesting, not just limited to surviving one more day. It would be a way to keep the character busy with more things to do, apart from living day to day.
I would make the achievement of these objectives difficult to reach, like a kind of ascent in "nethack", in search of the amulet of yendor, that would require exploring the map a lot to find what you are looking for, obviously taking advantage of the procedural part of the game. Of course, in each new game, everything has to appear in a different place. It might even make room to include new skills.
3. Random events and zombies.
The game would benefit from a greater number of random events. The helicopter is really cool, it's a shame it only happens once per game -I'm sure this is something you've been told many times before-.
As for the zombies, I would like to find them in more varied situations. Inside a wardrobe, under a bed, in the trunk of a car. I know the game is not designed for zombies to come out of containers, but wouldn't it be cool and scary at the same time?!
And what about the elderly and children? There should be zombies of different sizes and heights. Fat zombies, skinny zombies, people without a leg or an arm. Zombies with alternative behaviors that make them a little more unpredictable.
-- Well, I don't want to ramble on much more. I take this opportunity to congratulate the developers for the work done. I bought the game many years ago, even before it was on steam. And I have to say that I'm surprised at how much the game has improved, especially in the last two or three years.
So, keep it up!