I've never really had a Cap-ship, so the biggest ships I flew were Gunboats and Transports.
Each of my ships (Depending on their general size) had a different number of crew.
- I had a Bottlenose which was piloted by one single person, but him being a cyborg he could 'attach' himself into the ship main console and take control of all systems without having to run around the whole bridge and engine room and whatnot. He just gave the orders, and the automated systems did the rest.
- Or my Behemoth for example, had a crew of 5, only the Captain was RPed on server, but they also had a navigator, a medic and 2 engineers with them.
- My Raba as another example, even though still a transport, had 12 crew. Mainly because it was a combat ship and needed more people to get the ship running properly if things come to fights.
- My Junker Conference ran on a crew of 4, but that was only because I did intend to give it a low number. Because the ship InRp was put together by a small group of junkers who later decided to use it themselves instead of selling it. So, even though they barely could keep the ship running, they still managed, because -they- had made it in the first place, so they perfectly knew how it worked best.
- My Imperator, on the other hand, had about 25 people on board, just to express the feeling of a 'Heavy gunboat' with eight turrets and whatnot.
I think it's just a matter of size. I never Rped my bombers with more than 1 pilot. All my bombers were RPed to have an AI doing the co-pilot's job, and that's mainly why the 2nd pilot model in cockpit always bugged me. So if you ask me, gunboats logically have around 10 - 30 crew, transports ranging from 5 to 20 depending on their size, cruisers from 40 to 100 and battleships from 200 or 300 so and higher in case of carriers or juggernauts.
Although it's not really an important detail, and I really doubt most people would've even thought about it before seeing this thread, and I rarely see more than 3 - 4 crew RPed in game or on forums. So I think it's just the matter of imagination... You can imagine the Battleship in front of you with +1000 people on board, while the person flying it thinks of it as a battleship with 150 crew. Shouldn't really effect the RP that much to be a problem.