After 183 pages I am not sure if I even qualify to add to this discussion. It's an interesting topic, one in which I wouldn't mind giving my two cents to, but even after reading the OP and multiple pages, I am still a little unclear what this is meant to accomplish.
Is the thread merly to opine on the subject, or to ask why Bioware didn't include homosexual relationships?
If Mass Effect 2 had included same sex relationships (I guess a meaningful one, as they have a superficial female/lesbian one in Kelly) I don't think I would have minded as I could have easily chosen not to participate in such a relationship. So if the question is for opinions, mine is as mentioned.
Why they don't have them, well I will have to defer to one of the very early posts that quoted Ray Muzyka. Honestly, that is the way I have always looked at it. Both Mass Effect games for me, have been a story that I play one of the characters (as opposed to Dragon Age where I 'generate" MY character). In doing so, the story is laid out in front of me with a few minor forks and decisions to make. It's always been my opinion, that Bioware simply didn't want to portray any (or a good portion) of the characters in the story as homosexual, or with an option to be homosexual. Not saying it's good or bad, but that seems to be the direction they wanted to go with for the ME trilogy.
I know they are not entirely the same thing, but it would be a little similar to folks being upset that you can't play a female Gear in the Gears of War storyline. In the end, it's the developer's story that they wish to tell. The difference being that ME allows the players to impact that story on a very high level. Unfortunately for players who like to roleplay their hero as a homosexual, Bioware would like to keep the hero of galaxy a heterosexual.
As for a solution, I don't see there being one as it's their story to tell. I know it's a little disappointing to folks that would like to have the option, but that's the way it is. I like ME and the fact that they do not include same sex relationships doesn't bother me...I enjoy the story.