Just like how I'm not mad that there's an underrepresentation of Armenians in the media because I know there's a grand total of like five of us.
And they are all Kardashians. That and the fat guy from Borat.
It's like me saying we as a society have a problem with straight white people because we killed a billion Stormtroopers in Star Wars
Wouldn't the stormtroopers be gay? We never saw any women or prostitutes on the death star, so unless they had a sexy holodeck, those guys had do be doing it navy style. And since they were genetically altered soldiers, and considering their service record, it would seem cruel to not alter them into gayety. So that's my theory, that I just made up just now.
There's a reason queer people are more likely to die and least likely to have a happy ending.
The reason is tokenism I'd imagine. Most minorities have the same issue. Of course like Evan pointed out, background characters get killed regardless, but when it comes to writing there are a couple of reasons why this happens.
1: Most writers are straight dudes. Which means that most writers only intuitively understand the issues of straight dudes, and their understanding of women, minorities, and LGBTQIA characters is strictly intellectual. That means those characters end up as supporting characters.
2: Most things are written for their main audience, which is usually going to be straight white men or straight white women. That makes is more expedient to make a straight white man and/or straight white woman the main character, because it'll be easier for the audience to directly empathize with them. This isn't to say that the audience hates minorities or gays, but rather they have less in common with them. That means that minority characters end up as supporting characters.
3: Traditionally you kill the supporting characters, not the main characters. Some writers know how to circumvent this, but most still follow that style where you have a few main characters who live and any emotional deaths you write are pulled from the supporting characters.
Of course this doesn't happen all the time, and there are things written with minorities in mind. And I do suspect that this rule is held up by Hollywood more than it probably needs to be and just for bland marketing reasons. But I don't think it is sinister so much as it is just plain profit-motives.
This is not to take away from the tragedy that happened yesterday. And though there are fuck-loads if reasons swirling around, and we'll be arguing about what to blame for a long time going forward, I don't think fiction is necessarily on the list of culprits.