I wonder if those uniforms were suppose to be the mini-skirt uniforms that we saw both men and women wearing in Season 1 of TNG.
Kinda, but not quite. Here's editor Bob Greenberger's explanation in the letter column of issue 4 of the miniseries:
The Bickleys are of a race not yet revealed in the stories. Just as Worf modifies his uniform to represent his Klingon heritage, the Bickleys wear the capes as part of their culture. The uniform is also a modification of the coulottes many members of the crew wear.
That's right, the Bickleys weren't meant to be human, despite their name. Although I think the only indication of that aside from their costumes was a slightly reddish skin tone.
But what's with the super hero look?
It was designed by a comic-book artist. Not surprising that Marcos went with what he knew.