TL;DR: Let engine/backend be compatible with dynamically adding more area to map/world (unfixed world size), so that if modders would like to make a mod that creates procedurally generated worlds, that they won't be hard-stopped by the way the engine works.
IIRC Coffeestain explicitly stated that their game will not be procedurally generated. That's fine and dandy. If they want to artisan handcraft every map, power to the devs. All I simply ask (well, not really all that simple :P ) is for the way that the engine handles the map/world to allow for the dynamic addition of more map, per se. This would also include making sure that world objects and player structures don't have some fundamental dependence on the map being a specific, fixed sized. Imagine that every new world would be perfectly unique, and with granular control to factors such as biome size, how hilly the terrain is, resource availability, etc. I'm not asking for Coffeestain to do the hard work and create a world generator, but at the very least don't shoot themselves in the foot by making their base game fundamentally incompatible with it.
