I literally run a Mastodon server specifically for non-toxic English-first anime/etc fans and I understand where you're coming from. I created the community for a lot of the same reasons

That said, you are projecting an extreme puritanical Western philosophy onto a culture that is dramatically different for deeply ingrained cultural reasons.

Teenage stories are prevalent because of the concept "seishun" (springtime of youth). Japanese culture is extremely rigid and conformist, and as a consequence highschool is viewed as the time in life where you have the most freedom to try new things, express yourself, and discover your passions. Watching teens experience their first love, for example, is a cathartic release for people who don't have the freedom to make drastic changes to their identity anymore. It is a depiction of someone discovering a new identity, and embracing change.

"Kawaii" (cute) culture has deep roots in Shinto spiritualism. For a large part of Japanese history, due to mortality rates among children below the age of 7, children were literally considered not fully human until they reached a certain age. They were "close to the spirits" because they might be reclaimed by the spirit world at any time. This, along with some other tidbits, led to the trope where a spiritual being regresses to look childlike when they lose their spiritual power. It is "closer to the spirit realm". And because there are many stories about being careful not to malign spirits, this became a reverence for childlike things.

Yes, especially among westerners, the are a lot of people with transgressive tendencies who gravitate towards the medium because it's an easy mask for their predilections. But you would do well to more about the history of the culture and medium you're attacking.

Because the way you present your position right now just makes you look like an ignorant westerner who didn't bother to ask "why" before painting an entire culture with a single brush.