Remember this is my opinion and my opinion only. I have no delusion that my opinion = fact. That being said...
I will have to disagree with making all of the current romanceable options/companions Bi. Having a same gender attraction on any level just doesn't seem to fit with the character/personality of some of the companions. Some of them I can't really put a finger on why I feel making them be romance options to the male and female roles of each class wouldn't work, it just wouldn't. If I do have a reason why I chose what I did for each, it's noted. Also, sometimes you really can't tell if what a person's preference is by looking at them or hearing them talk for five minutes. Sometimes, it takes actually getting to know a person. Not that I know these characters very well...but you get the idea.
Just as an example, and I'm only going to mention the characters I or my husband have run across so far...
Jedi Consular:
Theran Cedrex: Bi/Gay. Could be the reason he has a holographic girlfriend...Just speculation of course.
Trooper:
Aric Jorgan: Bi/Gay/Straight... As of where I am in the game, he's probably the hardest to figure out, on the Republic side.
Elara Dorne: Straight. Personally, I think she's too conservative for anything else, as of right now anyway. (I actually had her in my party when I was on Nar Shaddaa. She really doesn't like it when your Trooper goes against regulation and flirts with the SIS agent. I did it just to piss her off. )
Bounty Hunter:
Mako: To be honest, she comes across as being a little sister to even be a romance option. That aside, I would say straight.
Smuggler:
Corso Riggs: Straight. It could be his good ol'boy attitude, or the fact that with him it seems to be "what you see is what you get", I don't know, but it just seems to me that he doesn't come across as being into men. Though, this could change.
Risha: Bi or just straight-up lesbian. She mentions having a history with an NPC on Taris. At this point, that could mean anything. Until I see what BioWare's future plans are with this char, I'm going with partners in crime.
Imperial Agent:
Kaliyo: Iffy/Bi. Of the characters I've run across this far in the game, she is the hardest to figure out. At least on the Sith side.
Again, what I have listed is merely speculation from someone who likes to write and pays attention to the character of people, fiction and non-fiction. To state the obvious, a lot of these characters have current story lines and personalities that could progress as the game progresses. It will be really interesting to see what BioWare has in mind for them.
Behind the scenes: 1- I wonder if BioWare already has some script written for future romance interactions. 2- It wouldn't surprise me if BioWare already has voice actors all lined up and ready to go for future story lines. 3- I understand this is a business and BioWare needs to do what is most financially beneficial to them (after all, if the company takes a financial hit because of a bad decision, future content will most likely not happen). If that means making the current companions/romance options Bi, so be it. 4- It doesn't matter how well a game is made or what changes are implemented , people will still complain. Not everyone can be satisfied.
Note: Sorry about the size of the font. My eyes are getting old.