So, full disclosure, I am cis, and exclusively attracted to men, since that is sure to influence my viewpoint on this.
I am of course referring to this: https://tvtropes.org/pmwiki/pmwiki.php/Main/EveryoneIsBi
I think that this is essentially the laziest way to do gay/bi representation. Everyone's just inexplicably bisexual. I'm sure some people are happy with that for whatever of what I am sure is long list of valid reasons. If you like games where you don't have to worry about this, I'm not arguing that you shouldn't. And I can't know how bi people feel about this at all from my experiences alone, so any bi people with an opinion on this please do share so I can further develop my own perspective on this.
Like, when I want representation, I kind of want it to reflect the real gay experience. That means the tragic bits too, including that not everyone is on the table as a potential partner. And that doesn't even mean having only one in ten or so characters being an option, I have seen VNs where there are so many gay people that it is clear that there is something in the water making everyone gay, that represent that aspect better. Something like getting the wrong signals and getting turned down by someone who can't reciprocate your feelings towards them? It's a tragic experience, but one that can be worth representing in media, because it's a real experience. But I don't know if that ever will be represented properly, queer people are already a small portion of the market, queer people looking specifically to be tragically rejected by a straight person have to be an absolute minority.
Why I say this is possibly a step backwards, is that games like Dragon Age: Origins (2009) had romance options that all had distinct sexual orientations, you had two straight and two bisexual companions you could romance. Fallout NV had no real "romance" options with companions, but did have Veronica and Arcade as distinctly lesbian/gay. And honestly, this seemed a bit more... it feels really fucking wrong to say "natural" in this context, but I will say it feels uncanny in comparison when I can put on a necklace in Skyrim and suddenly everyone I have run an errand for wants to marry me. Or that every companion in Fallout 4 will constantly forcegreet me after I max out friendship trying to get me to start their romance line.
It also just feels so much like an afterthought in comparison as far as the character writing goes. Looking at the games I mentioned, the distinctly bi and gay characters do feel like they have bi/gay energy, and that feels like it adds to their character design. I don't feel the same representation I felt with someone like Arcade Gannon in this type of setup, where there was a character who was like me (though to be fair I didn't know I was like him at the time I played -- well, I kind of did, but I was in deep denial at the time -- it's complicated), it just seems empty -- none of these characters are like me in that way.
Some people don't call this approach "everyone is bi", but use terms like "the gay button" instead. Because these NPCs usually aren't written to be bi. as a bi woman, i do not see myself represented in such characters. there'll normally be nothing in the dialogue showing that they are interested in more than one gender, they're either presented as completely straight if you romance them as a character of the opposite gender or completely gay if you romance them as a character of the same gender. in a hetnormative society, this makes straightness their assumed default orientiation and the queer content only shows up if you actively look for it by trying to engage in same sex romance with them. it does not become part of the text otherwise. so, you need to "press the gay button" to have queer representation in your game and if you're a capital G Gamer where the G doesn't stand for amazingly Gay, you are never bothered with queer content in your gaming experience at all.
You probably see were i'm going with this. Writing characters with a sexual orientation that behaves like Schrödinger's Cat is a lazy cop-out that tries not to offend anybody and ends up being offensive to everyone through this cowardice. You do not feel represented, i do not feel represented and if the straights wouldn't be so used to being represented anywhere, they probably wouldn't feel represented either. And it all comes at the expense of character depth, too, with these NPCs being straight-passing blank slates with a sexuality that works like a new skin or a palette swap.
they're not bi, they're playersexual. Really they should be making the straight coded behaviors different as well, why should the dragon age setting have the same norms as earth?