I wonder how people would feel about short capes. Short capes were all the rage in the 50s and 60s, but then in the 70s, people like Neal Adams popularized the long cape.
Ever since, it's been standard practice to draw long flowing capes. But then fans say these capes are impractical and they need to be gotten rid. But a short cape would probably work.
I personally hate short capes on Batman, since he uses them to misdirect criminals as to where parts of his body is, making them shoot at the wrong places, and because they can't effectively double as gliders.
Superman though, should have a cape that goes to at least his waist and no higher than the top of his boots, and preferably only goes to his thighs.
At least, in my opinion. It looks good without being too regal for such a hero of the people.