Yeah, I've always thought most structure was printed out in a honeycomb arrangement that would be extremely rigid in the large scale, but softer in the small scale. All with a skin of hardened armor. It would a fairly hard structure to "destroy," even if you put a thousand holes straight through it, and it would be pretty easy to patch up.
It would be a completely different sort of engineering compared to current shipbuilding, which is a steel skin stiffened by bulkheads.
I like the game too, but that doesn't mean you have to jump to irrational arguments to justify certain systems. For example in the real world a facility that produces 1/4 inch steel is identical to the facility that produces 1 inch steel because it's the same facility. The press that cuts the steel is the same press, and all of this assumes the ship taking reinforced bulkheads necessitates adding a "forge" instead of it being a drydock operation. But let's say you're right, there's no way in holy guacamole that a targeting computer takes up more space than a "forge", but the OP costs would indicate otherwise.
This is just grossly not true. No one can produce the 16 inch steel plate we used to armor battleships in WWII. The technology just doesn't exist anymore. Even on the human scale, sheers are used to cut thin metal, and abrasives or torch cutting is used for steel that is actually rigid on its own.
Adding a targeting computer isn't just a matter of finding a place to plug in your gaming PC. It's sensors, both primary and many redundant, run throughout the ship. It's coolant for a computer that is likely much more powerful than normal. All this has to run while being shot at, so that means crew training and damage control priorities that drag response time from other systems.
By the way, OP has been a good stand in for the cost of crew training and procedure that comes with some substantial piece of tech. It is never specified as purely power requirements or space, and the weapon and hullmod design has been consistent enough so that it all balances out so that it still looks like spending more OP is pushing the machine and the crew to the limits.