Why print a PCB module on ceramic?
This is a relatively inexpensive method of construction if you are making tens of thousands of units.  This is / was known as a "hybrid module" or "ceramic hybrid module".

Note that all of the resistors are screen-printed on the substrate (dark rectangles).  Also note that they can do multiple layers of conductors because they print insulating layers between each of layer.

Finally, because the resistors are exposed, they can trim each resistor before the final protective top coat is applied.  That makes this type of construction extremely attractive if the circuits require precision trimming.  You will see the trim as a laser cut in the resistor body - the cut is usually in the shape of a "L".  The short leg of the "L" is the initial rough trim, the vertical part of the cut is the fine trim.

I used to see this type of construction a lot for precision analog filters and telephone hybrid (2-wire to 4-wire conversion) networks.