Not only are they unnecessarily sexualised, they are also extremely impractical in most cases. For instance, why would a female character with no superhuman durability to speak of go into battle with heavily armoured and massively powered opponents wearing what is essentially a bikini? It shouldn't happen, but it does happen in comic books - and it happens a lot. Of course, there are characters whose durability is such that they don't necessarily need to wear full body armour in battle but, even so, revealing 90% of their body is still unnecessary.
superhero costume party
In 1974, Marvel Editor-in-Chief Roy Thomas decided that there should be a Canadian superhero, so he asked Incredible Hulk writer Len Wein to come up with one and either call him the Badger or Wolverine. Wein read up about wolverines and decided to use that name. When the character concept was developed by Wein, Marvel's Art Director, John Romita, was brought in to then give the character a look. Romita essentially designed a costume that made the character look like an animal. That was fine for his first appearance.
Part of the appeal of the character was his awesome costume, which was designed by C.C. Beck. Fawcett's attempt to make Captain Marvel different from Superman was to try to work the magic angle more with their character, as Billy Batson says a magic word, "Shazam!" to transform into Captain Marvel, Earth's Mightiest Mortal. As a result, Beck went for a more ornate costume than Superman's, with a lot of flair thrown into the design. Elvis Presley would later mimic a lot of the elements of Captain Marvel's costume for his Las Vegas show outfits. If your superhero costume is cool enough that the King of Rock 'n' Roll works it into his stage outfits, then we think that merits a high spot on this countdown.
superhero costume target
Pretty much every superhero in comic books has a superpower that isn’t really mentioned. Sure, some billionaire genius could, theoretically, learn how to build powerful metal suit and fight crime similar to Iron Man. However, that person still won’t have all the superpowers of Tony Stark. You see, Tony Stark is a ridiculously attractive man. Wonder Woman, in addition to being a badass warrior that could pretty much dominate any foe, is also incredibly beautiful. Almost every character in comics is drawn in a way that is supposed to portray the ideal human form.