The difference there is that those stories take place in a world that is not ours. Taking the concept of someone dressing up as a superhero and trying to fit them in our own world is never not going to be really, really silly. As opposed to something like Lord of the Rings where the entire setting is one of magic and weirdness, making elves and orcs - while silly - fit in perfectly fine without feeling like you need to slightly squint your eyes to not have the illusion break.By that logic we cannot take Lord of the Rings seriously or Star Wars. Or any epic heroes of legends and myth in the past. Because they are built upon things that in reality today we find absurd.
I can't take the story of Turin Turambar seriously because he's fights and kills a Dragon, a mere human doing that.
Also, the superhero genre seeming only has two states; silly, superhero fun and dark, edgey brooding. It shows how limited this genre is in creative freedom. Sci-fi, Fantasy, Horror, even Comedy has many faces. Superheroes only have two. There's really very little to explore other than 'Oh no, I have/others have powers; what do we do?', or 'Yay powers, woooo!'