The only reason I can imagine to ask people why they don't read superhero comics is because for some reason you want to make a superhero comic for people who don't like superhero comics.
This is a trap a lot of people seem to fall into. I've seen it over and over again, so I'm warning you not to fall victim to it. If you're going to make a superhero comic, make it for people who at least kind of like superhero comics, or like superhero movies or cartoon series (like Young Justice for example) but don't like mainline superhero comics. Nobody is going to read a comic that's like "this is a superhero comic! But it's not like other superhero comics!" if they're not motivated to even look in the Superhero genre to begin with.
Because the fact is that Superhero comics are fine at what they do, but what they do is very specific and not for everyone. It's generally some sort of soft sci-fi or Fantasy about people who use their extraordinary powers to personally overcome problems in society, often while wearing a flamboyant outfit, possibly with some kind of anonymity. It's a power fantasy about having control and agency.
Practically every conceivable deconstruction of superheroes has kind of already been done, like "ooh, what if the heroes were government sponsored and we explored how authoritarian superheroes are as a concept!?" Yeah, we've got The Boys, we've got Watchmen... Hell, even My Hero Academia is a bit like this. Or "Ooh! What if a group of superheroes refused to wear costumes and hated superheroes!?" Yeah, that's Runaways among others. "What if somebody with no powers tried to be a superhero in real life?" and so there's Kickass. "What if instead of being a masculine power fantasy, superheroes were a group of girls in cute outfits and there was romantic drama!?" -Yeah, that's Sailor Moon all right. 
When you're going to make a superhero story, assume your audience are people who at least like the concept of superheroes, because if you remove the elements that people who don't like superheroes dislike so much that they can't even read a less "typical" take on the genre like Watchmen or Runaways, you'll get something that isn't really a superhero story, more like... I dunno, a soft sci-fi or Fantasy story about people with powers (like Buffy the Vampire Slayer) if you take out the costumes and codenames (and my comic is arguably this too), or a story about vigilantes or a government task force if you take out the powers (like The A-Team).
There are a lot of people who love the Marvel movies, and maybe like some stuff like Young Justice or Teen Titans, and maybe odd comics like Runaways, Young Avengers, Squirrel Girl and My Hero Academia but don't like mainstream superhero comics, and the reasons are often:
- The characters are hard to relate to because they're usually exaggeratedly muscular and craggy white American men in their mid thirties.
- Politically superheroes are.... kind of an authoritarian concept that may not appeal to modern young people? Like the idea that if you have superpowers (or if you're Batman just.... lots of money?) it's reasonable to be a vigilante and go around beating up criminals gets deconstructed a lot for a reason. Modern superheroes have to do a lot more legwork to justify why being a superhero is okay, and tend to have to focus on big threats like a supervillain or alien invasion or have the characters answer to authority, and still a lot of people might just not like the concept of people who go around with superhuman abilities solving people's problems for them (especially with um... how this reflects American foreign policy in an uncomfortable way sometimes, as reflected in Watchmen).
- The art style, particularly in print superhero books, is very masculine and aimed at a pretty narrow audience. I say this as a person who was literally told by a Marvel editor that my art is too feminine looking to be in a mainstream Marvel book (yes, that really happened, he said if I worked for Marvel, I'd need to be on books like Runaways and Young Avengers, I'm just too girly to draw Spider-man). A lot of people preferred the art style and character designs of the cartoon series, but only more fringe books tend to reflect this.
- While attempts have been made to represent LGBTQ+ people, a lot of them have been um.... bad? Looking at you, Snowflake and Safe Space
A lot of readers want representation of queer identities because it reflects their experiences, but mainsteam superhero books don't always do it super-well. Honestly just any representation of marginalised people and even of just women tends to be bad due to how homogeneous the teams making a lot of Superhero content are, or editorial meddling.
- Plotlines tend to focus on the action, fighting and convoluted villain plots, while a lot of people who like Superheroes as an idea but prefer them in films and TV it's usually because they like the ensemble cast dynamics (which is why X-Men Evolution was my favourite version of the X-Men personally).
- When I started reading even "fringe" superhero books like Runaways, I had to catch up on an absolutely ridiculous amount of lore to follow certain plot threads. A lot of mainstream superhero books are from the "big two" and assume ridiculously in-depth lore knowledge, which is even a problem with the Batman comic on Webtoon; it assumes you know way more about Batman characters than somebody who has never read Batman and has only seen the films or the old animated series would know. People often prefer the movies and animated series over the comics because those don't assume you already know who Stephanie Brown, AKA Spoiler, is.
But... Obviously those aren't the thoughts of somebody who doesn't read superhero comics, so much as the thoughts of somebody who loves superhero comics as a concept and has read a lot of them, but would like them to be better and more accessible and even tried to work for Marvel to make it happen, and had a bad experience with the whole thing.
