I disagree completely with the idea of the option to pursue romance with all characters in an RPG (comes up during the question half hour). In fact, I think it's important that there are some characters you can't do this with.
In the real world, sexuality is rarely all-embracing. People have different tastes, orientations, or occasionally no orientation at all and these attributes hugely affect a person's life. While you as the player should be able to shape that aspect of your character, when it comes to NPCs, which themselves all have pre-written backstories, giving the player the ability to command such an important aspect of their character, in my eyes, devalues them as a whole.
For example, ME2 is mentioned as a specific example for where free romance should be used. Mordin however, is a Salarian. Salarians are an asexually orientated species, it actually says this in the codex entry. It would have made no sense at all for him to be a romance option.
In the end, my favourite characters from ME2 were Mordin, Samara and Legion. All 3 of which are non-romance (Slight question mark over Samara, but ultimatly all attempts are rebuffed by her, thank god). Somehow I doubt this is a coincidence (I am asexual myself, by the way). I think that, as a character, it makes little sense for Samara to find Shepard attractive. She's amongst the oldest Asari in the galaxy, long past her Maiden stage quite literally a matriarch, a mother.
Basically what I'm trying to say is that romance options are fine, but not if they don't make sense as part of that character. The game should be able to turn around and say, "Ok, you want to pursue the romance option with this same-gender NPC, but this NPC is heterosexual. So you can't. Tough luck." Forcing the NPC into a position that makes little sense based on their character backstory is even worse than them not having one at all.