So, I have this theory that it has to do with how women and non-hetero ppl, and people of colour in particular are marginalised in narratives and society in general (and to different degrees depending on intersections).
Most narratives revolve around white male people, so we’re socialised to accept their humanity in all forms—no matter if they’re they’re literally Satan—and to see ourselves reflected through them. My guess is that hetero white women are projecting their power fantasies onto the easiest characters to imagine themselves as: the characters with the most agency, power and privilege in society. I would say “the most well-rounded characters,” but even shitty weak white male characters have plenty of stans, so clearly they don’t have to be well-written—it’s just that we’re used to accepting these characters despite their faults.
Sexuality comes into play as well because female sexuality is demonised, so it’s more acceptable to explore male sexuality and desires. They’re also projecting their sexual power fantasies onto these characters.
Since people of colour are fetishised in varying ways, our sexualities are even less explored. Note how fandom perpetuates the racial stereotypes about black women being “strong” and not “needing” any lovers or romantic attachments. Look at the way fandom reacts to black female characters having love interests while trying to save the world—she can do both, but people don’t want to accept that. Our humanity and sexuality isn’t explorable for them—they can’t see themselves in us, no matter how well-written we are.
This is as much the fault of our society as it is the fault of the individuals who choose not to examine their prejudices when they have the means to.
It’s a perpetual cycle too because they’ve internalised sexism and are complicit in/benefit from racism from the time they’re kids, so they end up not being able to identify with female characters and characters of colour. This problem also goes unchecked because people think that women (predominantly white women in this context
because if we’re discussing Yaoi for example then it’s a slightly different conversation) writing white male/male pairings and participating in male slash fandom is progressive (I used to think like this and then thankfully the scales fell from my eyes).
I also think that white gay men aren’t only treated as accessories in media, but upheld as the standard of the lgbtq movement. Most of the representation goes to cis gay white men, so there’s this weird situation where people aren’t only fetishising them/their sexuality, but accessing their privilege.