Alright, here's a more clearer point:
Just how far do you want it to go before you're satisfied?
Sure, let's say we add in stuff like canals, and harvesting machines (as in simple machines, non-electrical. I hope the word "machine" hasn't been too distorted in our minds), and maybe let's even put in a husbandry program to teach the farmers how Mendelian genetics work many centuries before Mendel comes around. Ah, but wait! We have to consider that some regions have more than just plain old farming as its industry. Why should agriculture have all the attention! I say that logging, and hunting, and fishing, and mining, and stoneworking, and jewel crafting, all are just as worthy of attention!
Especially for places like mountains. What're you investing in when you make the investment then? The two sqaure meter patch of "farmland" in your estate's backyard? No, I say we invest in a mine!
Now let's make sure our mining is as well thought out as our farming, because we wouldn't like to be too heavily favoring a certain region type, would we? That would unbalance the game! So for mines, we can say we develop better drills, stabler shafts, better freight transport, among other things.
Then for forest regions, we can't forget logging! We need to have better woodcutting devices, better ways of transporting felled trees, methods to prevent insects and disease from killing them, more efficient processing of wood to remove leaves and bark, etc.
Fishing? It's not like farming at all! We need to allow the lord to have the option for better nets, or bigger boats, or more ports.
And you know what? All the aforementioned options should be different choices, with different effects on the production, and all decay at different rates due to different factors.
You probably think this is an extreme illustration, but I consider it a fair treatment of the other potential resource sectors. You can't just go on to invest and improve only agriculture, because the fact is, it's not just agriculture that is being affected when you invest. Food is only half of the picture. The other half has to do with the non-sustenance industries. Treat them with attention too, but how much are you willing to go such that first you would have features that you think are useful, and second, have balance in how much detail you have?
Hence why my main suggestion was just to make generic investments increase production in rurals by lesser amounts, but to have the food production cap removed. That way, to each his interpretation of what that investment actually is.
The complexity level is up to the devs. Removing the food production cap is of relatively little complexity. But there are desires to make the trading game generally more complex, by adding all kinds of resources: metal, wood, etc. It was also suggested to implement fishing as functioning differently than harvesting. Honestly, I like the trading game. It makes people interact with each other. It promotes cooperation and conflict all at the same time. And the more complex it becomes, the more opportunities there can be. And so I wouldn't mind specialized buildings to help farmlands, fishing, mining, and lumber, as long as their cost and upkeep make it balanced. But to what point do we want this aspect of the game to be complex? I don't know. It's hard to say what the impacts of the planned new economy system will be, and complexification would best be done after we get to experience it a little, rather than have massive new complex changes applied overnight. I'm confident that if it were just for food, and that it was a single building that could only be built in rurals and townslands and that had no consideration over what type of food collection was done, it *could* be implemented in a balanced way that does not impose micro-management on those who aren't interested, simply because rurals and pretty much everywhere on every continent. The same can't yet be said for the new economy goods, but I just like the overall idea of being able to build infrastructure to improve production, just as we can build new RCs or improve existing ones to increase soldier output.
