Yes, sounds interesting, maybe if one wants to try out a lot of prototypes and cut down on printing time. However, assuming you even want to make the face out of plastics, details might matter. The more details, the more difficult sanding will be. Don't know if other smoothing methods would work better here. Printing complex faces might generally be difficult.
In the Dollforum they discussed 3d printed molds for heads, but this is probably the same for faces: The best way seems to be, to print them as the first mold, sand them reasonably, use them as a mold for monster clay, remove the errors comming from the printed mold in the clay, work out the details on the clay, the use that one for silicone or whatever. Yes, it's complicated.