Complicating a feature of the game :O amazing idea! No really, amazing. I believe the game lacks specialization by allowing late game players so solo. What made me love wurm at first sight was how long it took to do anything, and i imagine living in a village with people who work their butts off in specific areas to yield amazing things. But instead what I saw were people who were able to accomplish nearly everything on their own and fight uniques together.
Only issue I see with the suggestion is that there is that complication of farming doesnt lead to NEW features, simply just a nerf. Now, theres no benefit to making the quality or yield much higher with how easy for a mid tier player to get large amount of crops (let alone a high tier), and improving quality wouldn't matter since its easy to become a good chef. The only benefit i see possible is to add new items as a result of the complication, such as decoratives from a rare yield. I would love it if I planted pumpkins on pumpkin season, watered them and tended them frequently, only to raise my chances of growing oversized pumpkins. Once that can make HUGE jack-o-lanterns. Or maybe make huge crop based figurines that can be burned to increase settlement bonuses.