Just like the Marvel Comics I grew up with:
From Siege #2, available at your favorite abattoir.
I once ran a roleplaying campaign that had this level of violence. It was a superhero-style campaign with adult themes. In the world that I created, there were no pre-existing superheroes. The meta-theme that I used for the heroes was that they wore the same costumes as comic book heroes so that the public would not be as frightened of them as they should be. After all, comic books were just for kids, right? The characters were mature, but very pragmatic in the treatment of their enemies. There was no superprison available to contain the extremely powerful criminals and some of them were quite horrible. Imagine a Hannibal Lecter-type serial killer, only with powers that make a straitjacket as effective as wearing tissue paper. In a setting such as that, it would be understandable to see someone in tights and a cape tearing someone in half.
In the Marvel Universe, it just seems incongruous to me to see someone clad in what is more or less a variation of Superman's costume, bathed in the blood of another humanoid being, while his victim's intestines literally spill out on-panel. At this point, let's abandon the costumes. They're not superheroes. There's no reason they should dress as superheroes. In a setting like this, there's certainly no purpose for them to wear the costumes. Masks to hide their identities would be appropriate, because I wouldn't want to show my face if I behaved that way.