The actual technical reason is that for a figure to be useable in the Face Room, there has to be morph control mapping into the face room system, as well as surface control of all the polypoints. That process is both timely and costly. Poser's owner(s) have set a cost to do it, and DAZ has said they will not pay it. So it isn't some bug in Poser, but DAZ refusing to pay to have their figures set up for use in the faceroom...