I'm just explaining reasons why I, and a number of people I talked to, didn't like it. I guess I should know better than to come to a fan space with a minority opinion. Sure, Bev is included in the group. It's also a boys space that thrives on period jokes, which is something Bev has massive anxiety about. Sure Bev might smile and nod and approve, but again that doesn't make things ok, it just means the filmmakers think it's ok.
What I actually think is that the dynamic of an all boys group that includes one girl that draws their attention and attraction is really lazy and unoriginal and does create problems considering how much this group dynamic gets reproduced. So many people keep saying "it's normal it's normal" but these losers aren't supposed to be normal (or are they?) and this is something straight out of the 60s. The film reads to me as something misogynist geeks would make after they grew up (vindicated for their bullying, loved for their humour, a pretty girl smiles at them and approves their behaviour).
I think you are hitting the nail on the head when you are talking about it dealing with a particular trope or storytelling setup that annoys or frustrates you (a group of boys and one girl).
You are right, it is based on something out of the '60s... almost. It's actually a novel written by a man in the '80s remembering his childhood from the 1950s and turning it into a story about remembering your childhood in the 1950s... which filmmakers who grew up in the '80s have transplanted to their own youth.
But on a larger note, I do not see how the boys are misogynistic. They are not woke in modern 2017 vernacular, nor would they be given the film mostly takes place in 1989, and kids unto themselves can be awful. Stephen King is aware that children can be cruel and monstrous. In fact, I think the movie smoothes out some of the most sadistic edges, like how Richie says racist things to Mike, and the latter just has to laugh along, and then yes Henry Bowers is much more monstrous (and openly racist) in the book too.
As for its handling of gender politics, I actually think other than the lazy and disappointing third act plot development of Bev becoming a damsel in distress, the film takes very painful steps toward addressing what you're talking about. Beverley is in a toxic situation at home with a father who demonizes her for her burgeoning sexuality. That same quality is why she is taunted at school, and how she is only now becoming aware of the power she can hold over men... including creepy druggists.
This is not demeaning her, but rather pretty sensitively dealing with the idea of abuse in a more sinister unspoken way that gets to plenty of subtext beyond just having her be physically beaten (which is what King mostly does until some rather grim third act insinuations that are more overt in the film). It is about a young girl who is targeted by everyone, except Pennywise who is an equal opportunist, due to both gender and class--do not forget a major reason she is targeted by her peers for gossip and crude rumors is because that in addition to having a period like Carrie, she comes from a poor home with a disreputable father. Parents talk. Kids use that as an excuse when she doesn't have the money or social support to defend herself.
It is actually pretty open in considering the role of sexuality in a girl's life when on the precipice of puberty, and it is giving a healthy message about her taking command and control of it. You criticize the movie for having boys stare at Bev, but that is what boys do, and that is also what Bev is considering. Her father leers at her; Henry Bowers leers at her; apparently the pharmacist leers at her. She is taking control of that and not in a sexual way, but in a self-aware and confident way. She is having to deal with a patriarchal world that victimizes women, and grapples with that in a sincere way as opposed to pretending it doesn't exist, which seems to be what many culture critics would prefer when they raise similar objections.
As for how the boys treat her; she is just another one of the club and not. They're too young to know why it's different, but they do treat her as their heart, because, yes, they all have a crush on her. That is not misogynistic, that is just a genuinely natural form of character progression in this situation. I find something like the much more saccharine Harry Potter books more of a problem as it doesn't actually represent genuine childhood emotions.
In any event, the book nor the film are perfect. I wish Henry Bowers had chased
all of the children into the sewers and that Bev was not kidnapped. And I wish
that sewer scene in the novel didn't occur. But if you think the boys are misogynistic for having a crush, or Ben is a date rapist for believing in true love's kiss, I think you are mostly just using hyperbole to exaggerate your disdain for the basic premise of the movie.