Why would this be the case? My best guess is that it’s because comics are about the most “fantasy” that you can get. Sure, other geeky things are fictional– you can give any amount of hit points to a monster that players must battle. You can dress a character on Star Trek however you want. You can make a character in a video game have breasts like beach balls. But in a comic, the character depicted is both a) visible and b) static. You can see her, but need not be concerned with how her body would move without violating the laws of physics in many directions. I’ve seen some grossly out of proportion characters in video games, but never one (for example) whose breasts faced the same direction as her backside. But that’s so common an occurrence in comic books that it has become cliche (ow ow ow, on that last one especially).

So having the ability to build a fantastic creation from the ground up plus the means to depict it clearly visually plus not being constrained in any way by physics is what makes it possible to dive head first into not only supernormal stimulus, but also fictitious and highly dubious psychology. Comic book women not only lack spines; they lack any concern about not having spines. They are quite happy to fight crime while clad in (sometimes only in) butt floss. Fiction’s handy that way– you can impose any condition on the characters and make them like it, because after all…you’re the story-teller.

In comparison, actual pornography seems comforting. At least those are real people (more or less), engaging in real activities that people can do in real life. But cross comics with porn and you get….animated pornography! No, I’m not going to link you to examples of such– you’ve got Google, and I don’t want to be responsible for introducing such a thing into anyone’s life.

(Hat tip to Pharyngula, where the following exchange took place:

P.Z.: I guess there’s a reason I haven’t read any mainstream comics in 30 years, too.
Antiochus Epiphanes: I can think of a better reason. Because you are a grown-up with access to actual books.
We Are Ing: Don’t hold your nose too much higher or you’ll fall over.
Ms. Daisy Cutter, Feral Fembeast:  Maus? Barefoot Gen? Fun Home? My Cancer Year? Fuck ‘em, they can’t be “actual books” because they have pictures an’ all. Antiochus said so.
Antiochus Epiphanes: To be fair, these are “actual” books, being bound printed matter. And one of them was awarded a Pulitzer prize. So there’s that. And you can read one in less than an hour which is pretty awesome if you don’t like to read.
stringer:  To be fair these are actual Scotsmen.

Fair cop. I’d recommend Maus, parts 1 and 2, to anybody.)