I come bearing another idea, and a bit of theory crafting. Had a few ideas on the first page of the conversation, but as I thought about it another idea popped into my head.
From a theory craft standpoint I guess the big issues with complex economics and intermediates is that its such a large amount of micro management that it becomes the game. Its why a lot of resource interchange games have very streamlined diplomacy and warfare. Also complex systems (and gamers who make them) hate interruptions. Not great when it comes to warfare and city capture and catastrophic economic failures. Another irk of mine is that complex economics often comes down to huge empires and sprawl, since you have to lock down certain economic points.
So my ideas on the first page of this thread were more treating resources as mini cities to keep all the economic webs in one place, and reduce the micro. But a totally different system popped into mind -- for lack of a better term, a guild based system.
The basic idea would be your populous is pretty innovative in a post cataclysmic world, and will find some way of doing what you want, even if its horribly inefficient. As a player, you would have your guild screen where you pick whatever end resource you want to have - say a sword. There would be no prerequisites or needed resources, other than the technology, and perhaps even that would be negotiable. Your guild would come up with the best way to make that sword-- automatically-- considering what resources and buildings you have. If you have iron and the like, great, its an efficient path with few steps and low upkeep per turn. But if you don't have iron, your people may use that ancient forest and perhaps that alchemy lab to harden the wood like iron, and a much deeper and more complex intermediate path, or maybe that lost library can find a way to harden your clay to fit the bill. Or perhaps you use a dozen specialists to scrounge the wastelands for old rusted weapons to melt down. The point being there's some path to what you as the player choose, it just might have a large number of steps (all of that taken care of by the guild automatically) that leads to a large upkeep in specialists/ gold/ food/ whatever.
To improve efficiencies of whatever path you're using to make your sword, the guild would use the questing system. Perhaps a large input of gold, escorting a researcher, clearing out a cave of beasts, providing a dozen peasants to dig somewhere, whatever. But the player could choose to activate the quests and do them, making a bottleneck step easier for the guild, reducing the upkeep costs to provide you swords. The intermediates that might be used in a lot of end products (like using wood+ magic instead of iron) that could be used in swords or armor types would then all have the bottleneck eased . .so intermediates are still important, its just that the player doesn't have to pay attention to specific numbers of any middle product, just the overall efficiency.
I thought it would be an interesting system. Its pretty straightforwards for the player - just say "make this available" and if you can afford all the upkeep its good - plus that strategic choice of how many specialists and gold to sink into any unlock adds some depth of choice. If you capture resources and there's a more efficient path opened up, the guild handles it without you having to micro your whole economic system. If you lose your cities, the same happens in reverse. Still the player does have continual input in the economics, and if you want to focus on quests for the guild you can, and make your economy more robust. Because of this a small but guild focused kingdom could end up making high end goods and not be dependent on sprawl or on any specific lacking resource as their economy would bypass it completely. The system could even be balanced to encourage small efficient kingdoms by adding a small tax multiplier for number of cities to the upkeep (for shipping/ taxes/ whatever). Properly balanced, the paths of producing end products in the most efficient ways might end up focusing players down production paths, and thus lots of troops based on iron weapons, or another race focusing on herbal products for their troops, since going outside those specialations would be inneficent without lots of questing for the guild, and not worth the upkeep and effort.
So just adding another possibility that would be streamlined for the player, but lead to some strategic choices and flesh out the economics. Will be interesting to see where everything ends up going as there seems to be arguments on if the system even needs changing at all, but I guess I'm all for something that adds a bit more choice and complexity so long as it is offering actual strategic depth and doesn't draw the player experience away from the central thrust of the game (the war of magic). Props though to anyone that spent the time to read through all of that.