This is indeed a good post!
I have been the farmer/provider for most of my games in ECO and the biggest problem is the amount of calories I waste basically Tera-forming an area to try to make suitable land, halfway across the world! I think tilled land should not be subject to numerous, ludicrous factors that can be messed up quite literally because someone places a block down near your farm. I think that with some slight tweaks you can make choosing the farmer role quite rewarding.
All I know is that for field crops we need to be able to choose a location and be able to grow crops from the get go (albeit not in tundra or desert biomes for the majority of plants), after gathering some seeds of course. You could even add in crows and other pests, give us other challenges to overcome to offset our ability to grow crops more readily. Keep the moisture, rainfall, temp, pollution and fertilizers, but get rid of "OVERCROWDING" that's not what it actually means anyways, and its garbage. Make it so the desert and tundra biome crops must be grown there. Maybe give us gardens (ie can only have 1 of them and can only grow a few things at a time) for non-farmers to start with to keep them working til the farmers start harvesting. Greenhouses mid-game for some of the smaller crops like the berries, beans, fiddleheads, etc. A tutorial for farmers would be a much appreciated addition. Livestock? maybe some specializations like shepherd. Get rid of digging from our tree and make a tree for builders or something, god-forbid make it someone you start with at max efficiency.
That's all I can think of for now.