The surface texture that's a result of the "printing" process looks like the surface of a metal casting when the parts are large scale (1/8)... but that same texture looks out of scale on smaller parts. So the problem isn't that you can't create smaller scale parts, you can... it's that the texture (which can't be changed) looks "too big" on smaller scale parts. The solution, of course, is to simply sand the parts smooth if you want to remove the surface texture altogether, like on bodies, no matter what the scale.
As the technology develops, the texture created by the "printing" process will most likely be eliminated... but like Rick says, where things stand today with this technology and with the costs involved, that surface texture is part of the process and you have to live with it (or sand it off!)