Certain EPs will lend themselves I’m sure to needing a new world. If this farming thing went the route of an EP and included a new world, I think that would fit. None of the current worlds we have really lend themselves to a true rural farming community feel. I think it’d be a mistake to create a farming EP and not develop a fitting world for it. However an EP like University for example could totally survive without one, they’d just need a college world. As much as I loved the different types of universities that came with TS2, the way they did TS3 was also fine for me. I’d be fine with one (or more) off map college world(s) that they go to just for their school terms and then back to the main world when they’re done. It just depends on the pack. But ultimately I’d absolutely take less worlds for better gameplay unless the pack wouldn’t make sense without a new world.
