Was it ever that weird? I feel Superhero fiction has always been for teenagers and kids primarily. What separates it that much from Tokusatsu, barring MA-twists where characters aren't really superheroes?
There are also a ton of comics aimed at adults, and I do not mean porn or violence. Just themes that are more in depth than simple heroes save the world stuff.
Plus most of what you are thinking of as for teenagers and kids is just aimed at all ages. The fact that we think being straightforward and without sex or gore is primarily for kids says a lot about us and not who is creating the comics.
I wasn't specifically referring to gore or violence, but themes - and I wasn't referring to comics specifically, just the bulk of superhero media. There have been some revisionist examples of superhero settings that take an established character and place them in a different context, with more adult HBO-esque themes. But the bulk of the many repeated releases for film every year don't seem to be of that nature.
Anything "weird" will change into "normal" when you get exposed to it enough.
Feel it strange to see a person with three heads once in your life?
Feel it strange to see a person with three heads after living for years in a country filled with three-headed people?
Or even just things like being around people with amputations regularly means some people lacking limbs is just normal. Or being around people with different skins tones and languages. Anything people are around enough becomes normal.
Not sure if the amputation part is sarcasm, but if new folks get born there, they surely have all limbs intact (unless there's a secret cult that creates amputees out of new peeps or something else crazy).