[couslee]

"It helps that they all use master computers, which cost a lot more than a bridge & life support & crew. The higher the cost of the support ship, the easier it is to retrofit it into a full warship."

That would explain my confusion. I ran into upgrade problems when going to imporve a light cruiser W/O MC. I had made the original design as mineral cheap as I could so that I could complete them in one turn. The upgrade had several changes made to it.