My first thought is that the time, trouble and logistics to transport the 3D builder to the site coupled with the site preparation, dealing with weather, excess room required for the builder would limit the type and frequency of structures that could be built.
In the end, I think that premanufactured panels, modules and components of a structure in a controlled environment would be quicker, more efficient and cheaper.
Maybe for building a base on the moon out of local media or something like that would be the best use....
just a few thoughts.
Your forgetting zoning, builder associations, trade groups and other regulations adding tens of thousands of dollars to the cost of a building.