Romances are a major element of many compelling stories, and Bioware has been writing them into their games since Baldur's Gate. Conversations about "game mechanics", as you put it, do not make for interesting characters, and character development is of primary concern in virtually any game by Bioware. I'd go so far as to say that their character writing prowess is one of the main reasons that they have been so successful as a developer. The fact that people connect with their characters enough to have huge discussions about them is a testament to their abilities.
I, for one, am not one of the obsessive fans who read or write fanfics, or profess to wishing that they were real people. I do find it a bit creepy myself, and sometimes they do go overboard with their requests. But you sound as if you're using people's behavior to justify the idea that romances should be written out to a minor role, whereas I simply take it as evidence that Bioware is very good at what they do.
Bioware is an experienced developer and a great story writer; although they DO listen to fans, they also do not let the fans write the story. Bioware knows where they're going with this game, and they have from the beginning. If the fans clamor for an element that can be added without compromising their vision, they will do it as long as they feel it can be done right. I don't see any problem whatsoever with this approach.