Hey, if we didn't have some appreciation for style-over-substance we wouldn't be reading superhero comics. It's one of the conventions of the genre. Non-flyers with capes still bug me a little, but I can live with them generally.
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...You are Number Six. Respect Popeye
I actually wonder if Superman and Batman, being created in the late 1930's, were given those different colour drawers for comic code reasons. The skin-tight look would make them look too naked, or something, so something extra was put on their groin and backside area. Because - those drawers serve no purpose. Captain Marvel got away with just a sash, maybe because his outfit was a little more baggy?
And think to the Silver Surfer in the 1960 to early 80's, with the silver shorts! Silly, no purpose, unless it was some decency standard or something.
So where does the whole cape & hero idea come from? CM's cape was inspired by pre-WWI British nobility uniforms. Didn't gladiators from ancient Rome wear those crimson capes for warmth and protection, especially in cold climates? I often think that way when I see Thor's cape; he's used it against cold and snow in his own book, and did so in Avengers/JLA.
The comics code didn't come about untill the 50's. The whole "Seduction of the Innocent" campaign was roughly concurrent with the Red Scare.
As to "Why capes?" I think it's a throwback to the swashbuckling heroes (for whom capes were contemporary fashion) from the Three Musketeers to Zorro, who had been revived in the Pulps not long before the Superhero era. Heroes wearing capes was already part of the Dime-Novel genre when superheroes came on the scene. Remember, Zorro was pretty much the direct inspiration for The Bat-Man.
Magicians, acrobats and strong-men also often wore capes in that era as well. Siegel and Schuster had moved Dr. Occult from a private-eye look to a cape look around the time they were developing Supes. In his case, I think his costume is more of a strong-man look. Remember, in the early days he was quite the macho man's-man; more like Popeye in terms of attitude than the Man of Steel we know. He didn't even fly in the early days, just jumped real far like the Hulk.
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...You are Number Six. Respect Popeye
While also propping up the cheesy notion that those little stick-on masks can really conceal your identity! Only Clark Kent's glasses are more unbelievable. I wish I could take every little mask like that off every character in comics, and make them go maskless or give them something bigger and better for most of their face.