I was not aware that the companions were either awesome or famous. The only character I noted in the game that was considered either awesome or famous by Forgotten Realms lore was Volo, who is an NPC and not a playable character. They each have what might be termed "interesting" or "unusual" backgrounds, but I can point to plenty of folks in the real world who fall in that category. And as these are new characters, not continuing cast from BG1 and 2, it makes sense for them to be lvl 1. BG 3 is NOT picking up where it left off, with lvl 20 characters created under 2.0 rules.
As for the rest, it seems you are the one typecasting them - they are presumably portrayed as they are for romance purposes, as the Developer wants to reach out to as many potential customers as possible - straight, gay, bi and whatever comes between - but none of them are "flaming" as you call it - Asterion is a prime example of what the European Aristocracy were like in both manner and dress - there is a reason they are often referred to as "foppish". I may not be a fan of the chosen personalities, but there is no reason to bring what sounds like bigotry into a computer game.
My issue with creating companions that do not have a specific preference is they all sound like they want a romance with your character. It’s annoying when your character just wants a good friendship but the companions keep flirting with you.
Hardcode their preferences, whatever they are. I’m not so insecure that I need my ego massaged in a video game so I need to be attractive to everything. If I fail because the companion isn’t into my character’s gender? So be it. I’ll roll another in a future run if that’s important to me.
When you try to please everyone all the time, you end up pleasing no one. A famous Aesop moral.