I don’t think it is necessary to lock characters to a specific preference. I don’t see how that would objectively improve the writing. Having characters with a specific preference does allow you to tell specific stories about how that affected their backstory, but that doesn’t need to be part of the story in the first place.
Due to the nature of games there is going to be a finite about of content for each companion’s dialogue and backstory. The writers can fill up that finite space with some other compelling content. The trade off for the lack of specificity is an abundance of player choice, which is preferable for me. Why write separate stories for straight and gay relationships when they can write relationships that satisfy either type?
To me being able to tell specific stories is the improvement I'm talking about, a story about a gay or straight person is going to have more character than a story about a gay and straight character...I mean "all of the above" sexuality. Don't misunderstand me I'm not saying a characters stories should be solely about their sexuality but that being written with one is better than being written with all of them
Sure, ideally for at least a few of the characters their sexuality should be part of their backstory (though in a setting with no orientation based discrimination or bias it probably wouldn’t be as significant a part of their personal history) and in this ideal scenario the game would adjust itself to accommodate this. For example, if I romance Gale as a man I get slightly different interactions than I do as a woman, and his background is slightly adjusted in the dialogue to reflect this. However, this is a fair amount of extra work for Larian with a minimal return, and they can still write compelling story content where the tension and internal conflict is independent of the protagonists gender. This allows them to use their finite resources for something else, and I much rather they do that.
The only thing I want them to do is adjust the way the game introduces potential relationships, which is to say, there should be some dialogue interactions before the party that allows the player to inconspicuously choose whom they are interested in so we don’t get bombarded with requests for sex from every party member all at once. Other than that, I think how they are handling it is fine so far.
No gender locked romances providing for maximal player choice is the way to go. There aren’t a ton of companions. Unless things change just 4 of either gender. For the ladies, one is a
withered old halfling granny who probably smells like wet dog
and the other is a bellicose frog lady. So assuming neither of these are appealing we are left with Shadowheart or Karlach. If Larian arbitrarily make one of these strictly gay and the other straight, then for lots of people there is only one viable option. No thanks. A bit of choice is better than none.