Superman is, and always has been, about his supporting cast.
Batman has a supporting cast, sure, but it's basically composed of colleagues in his fight against crime: Alfred, Ace, Dick Grayson, Jim Gordon, Harvey Bullock, Helena Bertinelli, Barbara Gordon, Tim Drake. Those who aren't crimefighters don't get a lot of air time and/or fade away. All the Julie Madison types come and go; Lucius Fox has been seen only once, I think, since No Man's Land (he needs a role in the fight, as he got in "Batman Begins"!); even Police Commissioner Akins has virtually vanished because he doesn't "partner" with Batman.
But Superman? It's all about Clark Kent's friends and family: Ma, Pa, Lana, Pete, Lois, Jimmy, Perry, even Jor-El and Lara. Superman's "colleagues" (Supergirl, Krypto, Steel, Superboy) just seem to be, well, in the way (see illustration).
Tonight for fun, try to write 12 consecutive stories where, say, Superman, Superboy, Supergirl, and Krypto all show up to take on the same menace; then you'll understand why the "super-allies" are kept at a distance: Superboy, banished to the Kents' farm; Supergirl, shipped off to Jim Lee's Glamazonia; Krypto, exiled to the Fortress; Steel, crippled.
Some people claim this difference between Superman and Batman as part of the proof that "Batman is the real identity and Bruce Wayne is a persona, whereas as Clark Kent is the real identity as Superman is a persona." To which, I say, "Piffel."
Like many straight people, Bruce and Clark make most of their friends through work. Bruce's only job is as Batman, so all his friends are bat-allies. Clark has a job as a reporter, and so his social life revolves around that. Even when the writers tried to give him a super-pal, the retroactively hiLARious Vartox, what does Clark do? Gets him a security job at the Daily Planet and names him "Vernon O'Valeron". By the way, changing my name to "Vernon O'Valeron" is now one of my Life Goals, so if you run into someone by that name, say hello nicely, because it will be me. You'll recognize me by the outfit.
Any way, there are some unpleasant consequences of Superman's supporting cast being so overwhelming important.
1. In order to keep Superman's cast interesting, writers are drawn to make them suffer bizarre experiences. We could talk all year about the wacky adventures of Superman's various buds, but instead we'll simply let one "Jimmy Olsen" cover serve as a symbol of this obvious and ridiculous truth.
2. If writers do not wacky-fy Clark's human entourage they become ... boring. No one's known what to do with Jimmy Olsen since the Byrne reboot, they gave up on Lois and just slapped a "Loyal Wife" label on her, and the less said about President Pete "Hush, oops I mean, Ruin" Ross and his wife, Lana "Manhunter cum Insect Queen" Lang, the better.
3. Superman's rogues gallery is wan and uninteresting because the focus of stories isn't Superman versus his enemies -- conflicts with villains are used mostly to highlight Clark's relationship with his buddies. Lex Luthor only survived because he was retconned in a "former friend gone bad"; c'mon, how many heroes call their archenemies by their FIRST NAMES?
4. Superman stories tend toward petty interpersonal melodrama. This why it could so easily be turned into Smallville's painful hybrid of the X-Files and Dawson's Creek. In a Batman story, you'll get Batman versus any one of about 400 freaky villains who could credibly kill him. In a Superman story, you'll get pages of sob & choke as the supporting cast fusses over the ups and downs of their relationship with the Big S.
The Superman mythos is a fetid, inbred, Peyton Place.
In fact, if I had any guts, I would publically admit that secretly I think Superman, DC's heroic archtype, is for the most part a weepy whiny Marvel comic and that Superman should be my next "Character Donation" to the Marvel Universe.
But, of course, I don't have the guts to admit that.