So, at the moment, we have herbs in bogs, and crops everywhere else.
Unless, or until, we have "variable" plots, this will essentially create a bifurcated body of suppliers, wherein crop growers will -- likely -- vastly outnumber herb growers.
My proposal here is to come up with a "third climate" and a "third class" of crops that can only be grown in certain regions.
What would this look like?
At first blush, one could posit mushrooms (and broaden the number of kinds of mushrooms): There might be some exclusive to alpine areas (ala Rasana), and others might be exclusive to forested areas (Groddle). Others might be exclusive to Uralia, and only be able to be harvested from patches (they would spring up, much like rocks do).
Another approach, might be -- if we had desert like areas -- cacti, again with various properties.
Or, if we had beach like areas -- seaweed.
Alternately, we could simply expand the type and number of herbs that can be grown and pay close attention to microclimate. Some herbs would be swamp only, others would be alpine, others dry-grassland climates (Aranna).
In this last scheme, it would force the behavior of what you can cultivate depends on where you live, and then drive profit-motivated Glitchen to live where the best upside for their harvest can be found. Which could help spread more folks into different kinds of housing, ala Muufo, and other (air-quote) less desirable (/airquote) areas. Right now, and I only know this anecdotally, but it feels like folks are concentrated in the bogs, or in near-Groddle areas.
I'm in favor of all of what I propose here, but I think attention to microclimate-based planting has the most potential to stimulate new player behaviors, with, one hopes, the least amount of development work.