Name one IRL Fighter craft that has internal room for you to go into the back and take a nap or a take a bathroom break / shower?I would class 'fighter craft' as vessels that are the size of a Shuttle and Runabouts (Delta Flyer included).
The only thing remotely close to that is the B-2 / B-1, those are "Tactical Bombers", not "Fighters".
You can't be wasting Volume / Mass for those amenities.
Maqui used old courier ships because those were easily available for them to get ahold of and retro-fit.Once you reach the size of that 30 year old Starfleet design which the Maqui used as a raider along with Raven class (7's parents), those and anything above would likely fall into full blown starship category (or basically, anything that has 2 decks perhaps?).
Not because they were purpose built.
What the Maqui's did was basically the 24th century equivalent of Al Qaeda strapping Machine Guns to a Toyota Hilux.
And "The Raven" would be about the size of a small warehouse that flies, it's not a small craft at that point, but it's not quite normal StarShip size either.
It's in that weird "Mega Yacht" size that is in between a Shuttle and full blown StarShip.