As has been said above,wood was used because of cheapness,ease of working.availibilty.
back in the day,the best of the best did not have wood scales.
The great blades,The classic blades,should IMO be dressed in scales of the period they were made at any cost,thats true restoration and preservation.
To see great blades dressed in gaudy plastic,multi colored Micartas,things that did not exsist when the razor was made makes me sick,But again,JMO