Length: 19 kilometers
Full Complement: 279,144 Crewmen, 1,590 Gunners
Minimum Crew: 50,000 Crewmen
Fighter Complement: 144 TIE-Fighters
Passangers: 38,000 Infantry, 40 AT-STs, 30 AT-ATs, 200 Support Craft, 3 Prefabricated Bases
Lack of consideration for scale and logistics a sad state of affairs within the sci-fi hobby that most fans are aware of. Science fiction franchises used to have some decent ideas about the scale of what they were depicting, but it's been eroded in the last couple of decades. A common peeve for many Star Wars fans, is the smaller and smaller units seen fighting in the Galactic Civil War. It's now often just single fire teams. I know that war is assymetrical, increasingly decided by smaller forces, but Coruscant alone has a population of 2 trillion. Just one planet. Compare to Russian casualties in WW2, where the Soviet Union had a population of only 170 million. The Empire could just throw bodies at the Rebellion.
JJ Abrams in particular lacks an imagination, always shoots films for spectacle, so all his starfighter dogfights are essentially conducted at World War I altitudes above planets, to give audiences placeholder references, as if starships are intended for the aerial theatre. Franchises made mistakes or stylistic choices before of course, but there was also sometimes ambitious in their depiction of scale. Star Trek is smaller scale than Star Wars, so works a bit better. As you say, a single Lexington-class Carrier in WW2 had a crew of 2,791 despite being shorter than James T Kirk's original USS Enterprise NCC-1701, with a crew of 400. However some science fiction depicts automation of systems, and small crews.
Here are some interesting stats:
- - By the end of World War II, the United States Navy grew to 1200 major combat ships. This included 28 aircraft carriers, 23 battleships, 71 escort carriers, 72 cruisers, over 232 submarines, 377 destroyers. Roughly 35,000 officers and 300,000 enlisted crew served at once. 3,500,000 total.
- - The Lexington-class Aircraft Carrier had a crew of around 2,791. The New York-class Battleship had a crew of 1,042. The Casablanca-class Escort Carrier had a crew of around 910. The Somers-class Destroyer had a crew of around 294. There were more than 100 classes of warship in operation.
This is the "my franchise can kick your franchise's ass" sizequeen syndrome.
In their defence, Warhammer 40,000 isn't going for realism. It was originally a parody of science fiction's inhuman scale. The Imperium's ships are barely understood by their crew, probably once having been automated hard-sci-fi behemoths with tiny crews. Now, in an age of decline, ignorant crews must physically load skyscraper-sized shells into Macrocannons when firing, like an 18th century Man-of-War.
Also Warhammer generally does depict huge battle fronts across entire continents, millions or billions of infantry, massive logistical considerations, etc. If science fiction is forced to scale down a little, for the sake of television, I'm okay with that. It's just become absurd in Star Wars's case in particular.
Carriers don't actually make that much sense in space, unless you twist the rules of the setting by having, say, big, largely immobile jumpships carrying attack craft that can't. The moment you install warp drives on your fighters or make the encumberance of carrying these systems too low, the niche for Space Fighters vanishes instantly, because they otherwise make about as much sense as having ships that launch squadrons of attack motorboats. There's no advantage here that planes are gaining by being in a different medium and thus following different rules. To have Space Fighters make ANY sense, carrying the drives you need for long-range space travel need to be a REAL impediment to engaging in combat. Otherwise you just don't use fighters.
Star Trek is actually thus fairly coherent; no carriers are ever officially shown, and fighter sized vessels are depicted as motorboats.
Fighters are usually just in science fiction because the author loves aviation. That's it. I've got no problem with Star Wars, Babylon 5 or Battlestar Galactica doing their thing, but you are right; they wouldn't seem to make much sense. You could argue they have low mass, for quick Newtonian maneuvering, but then a drone, not as vulernerable to G-forces, would serve that purpose far better. Star Wars, original Battlestar Galactica, and sometimes Star Trek, don't show Newtonian physics because A). it was hard to model before CGI, and B). it's a stylistic choice to ape WW2-style atmospheric combat for Star Wars in particular.