The 'D-mod ships are the norm' thing the story (used to?) want to have can't readily be explained by inability to manufacture pristine components, now that every faction except pirates and Pathers have at least an orbital works and degraded nanoforge. Combined with 10 stability and doctrine bonuses, this gets Diktat up to 90% quality ("average 1 D-mod per hull"), and even Church gets 65% ("average 2 D-mods"). Hegemony's quality is 95% (no D-mods on average), and Tri-Tachyon is 115%.
So if the issue doesn't come from garbage being rolled off the assembly line, where is it coming from?
The answer came to me when reading
this article: insufficient production/maintenance capacity for navies to consist entirely of pristine ships. During peaceful periods you could just scrap or sell anything that's too wrecked to be worth repairing (e.g. the Afflictor (D)'s description), but not in wartime (which damages or destroys the said pristine ships, while also greatly increasing total ship demand).
You know how after a battle, we players are offered a whole bunch of D-modded ships to salvage (but rarely take any of them)? That's where all the clunkers in circulation are coming from. Someone else takes the junk ships we leave behind and presses them back into service because they're needed and better than nothing.
The specific gameplay proposal:
- When an NPC fleet loses a ship, the faction's "D-mod score" is increased. Same if a raid sent by the faction fails or such. The score decays over time.
- When generating a new NPC fleet, the D-mod score is compared to the faction's ship production capacity (in my previous suggestion this would be the fleet spawn point pool; else you could take a snapshot of current production). Do some math with the two numbers to generate a penalty to the fleet's ship quality.