The general theme seems to be, I should be able to reveal my sexuality to my companions. But, in all seriousness, there's like 10 conversations per companion and most of them involve the companion telling you things about himself/herself. While its true that I can't tell Corso I dig the way his armor bulges, I also can't offer him a joint, tell him I prefer basketball to baseball, find out if he prefers kung fu movies to romantic comedies and so on and so forth.
The companion conversations are really there, for the most part, to drive the story. The real role playing is what you do when you interact with other players.
Thing is, what you're talking about isn't really what people here are asking for. At the heart of it, what we're asking for is equality - to be able to represent our characters' sexuality as we want to, and to not be forced into playing our characters as either straight or asexual. You can talk about RPing all you want, but as of right now, the actual game doesn't recognize homosexuality as being an option. Being able to play a character the way you see them is a huge part of a role-playing game, and having only one side represented in this game is more than a little unfair.
Still, not that I oppose same gender companions. I'm just against the reworking of old companions or the "paint the world bi" solution of dragon age 2.
Bear in mind, though, that this is a galaxy where there are tons of sentient humanoid species, and inter-species relationships don't seem to be anything unusual. Sexuality is bound to be more fluid. Someone could be attracted to only the opposite gender of their own species, but find both males and females of another species attractive, and so on. Options, man.