That's a good point. The bright colors, capes, masks and insignias all served a useful function. The goal (until recently) was for quick decisive recognition of the characters. That's why they tended to wear the same civilian clothes and props nearly all the time, whether a bow tie or a fedora at an a angle or a cigar stuck in the corner of the mouth. This seems to have been played down over the years, with more natural, muted colors, to the point where comics have actually become a bit drab.