Sexuality isn't a character trait. People just link arbitrary behaviors to certain genders and sexualities. Who you want to fuck does not define character. As you said, there is no reason to point out what sexuality someone has. If they have relation with a person of the same sex then they're gay, big whoop. Why make a big deal out of it?
No one needs to declare the sexuality of any character because it simply does not matter. If you want to have romance in your story then by all means do it, people will figure out pretty quickly by themselves what sexual orientation someone has. But boldly proclaiming that a character has a certain sexuality even though we know next to nothing about him is just exploitation. It shouldn't matter what sexuality a characters have or how many LGBT characters there are. It's simply irrelevant.
Know the first rule of story telling? Show, don't tell.
But who are you claiming is telling and not showing? Naughty Dog for showing two girls kiss when we see way more explicit things between straight characters all the time in media? Was there a section in that or any of the examples you can think of where the trailer or the game itself showed the character making a big deal about his/her sexuality or wearing some rainbow flag and marching in a parade for a mini-game?
I really don't see these character's actions as anything different than what has been done with straight characters. They aren't outing themselves in these games. They are just behaving like any person would. If they are gay, they show sexual interest in the same gender just like if they are straight they show that interest in the opposite.
And does sexuality not need to be declared only if the character isn't straight? Because I didn't hear any of these characters say in a trailer "Hey, I'm here and I'm queer," just like I didn't hear Geralt say "I am a man-whore" even though he's bed countless women (and without the need for protection because he's immune to disease, the lucky dude, but I digress).
Why are we still talking about this if sexuality isn't important and why do so many people only feel its worth talking about when sexuality is not represented in by what they consider normal?
As for the media or interviews highlighting that these characters exist, why is that an agenda and why do you not want to hear about it? It's news because it's rare. Imagine if people said, "who cares about race" when Jackie Robinson broke the color barrier in sports. To many people, it was newsworthy, because it was unprecedented and definitely out of the norm.
In a few decades, nobody is going to say "wow, we have a gay character in a game" in the same way that nobody says, "wow, a black guy is a professional athlete!" But until that time comes, people on both sides are going to make a deal about it, and I think that's an appropriate response.