I like talking about this topic, and I tried to resist this thread, but couldn’t, so here’s an essay. XD
A quick note: what I’m going to say is mostly about the writing of the main character. The way authors write all the other characters should be under their full control, but in my opinion, when writing the MC, the interactive aspect of IF requires them to acknowledge the vast diversity of people who will play their game.
I believe that each person’s opinion on this topic will largely depend on their personal relationship with things like gender identity, gender expression and gender norms/roles, and it’s important to recognise this when discussing such topics.
If a book has gender differences in writing, or is entirely gender-locked, that will most likely be influenced by gender norms that exist or are inspired by our real world. Why else would one choice or action “feels” appropriate for one gender, but not for others? Why is it okay for a woman to flirt a certain way, but not for a man? It’s because we were all socialised to expect different genders to behave differently. These rules are socially constructed; such gender differences are not an innate part of humans that is shared by all people of the same gender without exceptions.
The gender expression of most women and men aligns with what society expects of them, so is it okay if the writing takes this into account and tailors the narrative in a way that makes playing as different genders feels unique? No, it doesn’t make it okay. There are people who are gender non-conforming, and it isn’t fair to exclude them altogether, or make their narrative less immersive simply because they are a minority. The issue of gender norms is, of course, bigger than IF, and it’s not the writers’ job to combat gender stereotypes, but I think it’s crucial to remember that many people seek escapism in fiction, and for some, it is the only place where they can safely explore and express their gender, so in my opinion it’s important to make a book as inclusive as possible.
I intentionally didn’t mention non-binary people in my previous paragraph: their situation is more unique since gender norms are based on the concept of binary. I think that may be the reason why some stories in which gender plays a big role tend to completely exclude non-binary identities. Non-binary people aren’t expected to follow the same rules as men and women are, so it’s harder to tell what would be the non-binary version of an interaction that clearly has a female and a male variant. A lot of authors seem to simply place them in-between masculine and feminine, which is not how non-binary people work: there are non-binary people who expresses themselves in a strictly masculine or a strictly feminine way - they don’t have to be androgynous. Just like women don’t have to be feminine and men don’t have to be masculine.
There’s nothing wrong with a writer wanting to include gender-related reactivity in their book, but I believe that it would be better to base it on gender expression rather than gender identity (or on a combination of both.) Imagine a scene like this as an example: the MC is in a direct confrontation with a bad guy. If the MC is a man, the bad guy is intimidated and thus treats the MC with more caution, which makes a fight with him more difficult. However if the MC is a woman, the bad guy overestimates his own abilities because he thinks that as a man, he can easily overpower a woman, so the female MC gets a chance to catch him off guard, which will make this scene different compared to the male MC. These scenes will only work with at least somewhat gender conforming MCs, because there is no way this sexist guy would treat a feminine male MC as seriously as a traditionally masculine man. And what if you play as a masculine butch woman, would he underestimate you just as much as a fully femme presenting woman? Probably not. Once we acknowledge how unique humans can be, things aren’t so black and white.
Gender expression can be included as a separate choice (like some books do this already), or there can be a few versions of interaction that feels more masculine, feminine or gender-neutral, and then players are allowed to choose what fit their MC. This is so much better than enforcing gender norms on the MC. The other characters can also react to how the MC expresses themselves, they don’t have to completely ignore it along with their gender identity: for example, they can be more surprised if the MC acts outside of gender norms, and even judge them if the setting is more restrictive in this regard, so this doesn’t mean that a book can’t be “realistic.” But the options available for the MC shouldn’t be limited in the first place. I think it’s entirely possible to create a story where gender matters and that is also inclusive for various types of MCs, but unfortunately a lot of these kinds of books seem to simply rely on stereotypes.
(It can be a real urge sometimes.)