Uhhh I think the main thing is that there should just be more fully developed characters. I hate bad boys (though I like the physical aesthetics of like tattoos and piercings but IRL these things aren’t specific to only bAd bOyS) but bad boy characters are always manipulative and controlling and abusive. They’re cold and use women and for some reason see the “””shy nerdy MC””” and are instantly attracted to her. Then they spend 20 chapters being a jerk and the MC is like “oooo but I know they’re good deep down.” And then the bad boy is like “I know I’m a jerk but you have been putting up with my BS for so long so that must be what love is” and then they get married. So yeah, I’d say it’s pretty bad. They shouldn’t be replaced by underdeveloped “golden boys” either (who generally turn out to be just as controlling and manipulate but they are also good at sports and don’t have a tattoo so they must be a Good Boy).
Developing a well-rounded personality with believable flaws is important for a story. One of the basic aspects of storytelling that these stories are missing is that the characters should drive the plot. The goal isn’t to go from abusive characters to shallow but “nice” characters. You can have characters that are emotionally reserved but not uncaring. And more than that, there are thousands of other flaws for characters to have besides emotional repression. But if you’re going to have that as a main flaw or point of interest for your character and they’re an MC or LI, the character should still have people and values they care about; you still want them to be likeable and you want readers to root for their personal and relational development.
Are mean girls necessary? Uhh nope. I mean, having external conflicts in a story is totally valid, but if you have an antagonist they should also be well-developed so your readers are trying to understand what makes them do what they do. A mean girl character or similar antagonist who has no real reason to hate the MC doesn’t add much to the story. If you can replace the characters and have the same story, that means your characters could use more development. I’m also…like, I know girls and women are socialised to see other women as competition but it would be great to see more complex narratives than “random mean guy likes the Mary Sue so I must destroy her life.” Not every woman character has to be super nice and kind. In fact, giving complex histories and rich development (even if they’re an antagonist) is one of the best things you can do to show the variety of personalities women can have.
But if it sells to write these whirlwind romances with a kind of self-insert character, then I don’t see these cliches changing much. That being said, there are still thousands (??? I’m guessing lol I definitely haven’t read all of them) of stories that avoid these cliches or subvert them. There are so many community authors writing stories that are rich in detail and development, so there’s still plenty for me to read, personally haha