Facial feminization surgery, for the most part, involves removing bone, cartilage, and soft tissue in the forehead, orbitals, upper lip, nose, chin and jaw. To masculinize someone's face would require the opposite, i.e., adding bone, which is much more difficult. Bone fillers, implants, and relocation are possible but often problematic (infection, migration, necrosis). I'm not surprised it is not all that popular.