Complex crafting systems, are not to my liking. Spending hours onto gathering ressources and then somehow forging out of those other stuff. I do like the part of creating a village or houses though, perhaps in that way later also castles. But the system to do so shouldnt be too complex or time consuming.
The terraforming engine seems to do quite a good job though and such thing would be perhaps also nice to have for M:BG/E.