I think it is the exact opposite - video games allow for a different level of immersion than passive mediums like movies or books. There, you observe two characters interact and its fine to watch that happen for most people.
For video games, you often become your character, or you are roleplaying that character and in their head. And, in a sense, Bioware is putting you into a situation where you are simulating a romance with a fictional, virtual character that culminates in sex with said virtual, fictional character.
In that sense, Bioware has created a piece of fiction for you to have sex with. That's really kind of creepy when you think about it.
In regards to immersion and roleplaying;
To me, it is, for the most part, little different than when I write a character for a story; I create a character, decide their appearance and then shape their identity in accordance with the setting of the story. During the story, I attempt to make decisions and select the dialogue options that make sense considering the character with possible character developments they might have undergone in mind.
I rarely, if ever, decide to do a romance solely for the sake of a romance; the romance is not the focus, it compliments the story. If I do decide to do a romance then it'll be because the romanceable character is someone who I feel works with the player character. It's for the same reason I don't let my companions' approval or disapproval dictate my decisions on major issues or those considered major to the character. On some issues and depending on the character, I may decide my character can be a bit softer in how they voice their disapproval or disagreement while on other issues they feel stronger about, they may not be.
TL:DR - To me, romance is more like watching two virtual characters with each of their own stories and character culminations have a romance that compliments the overall story and their respective characters. I may be in control of the character but when I make decisions, I try to never insert myself into their character beyond trying to look at the setting from their, cultural and biased perspective.
As a note; The inclusion of sexual interractions never made a romance to me either and I always disliked when stories attempts to tell me that a character's lust for another character means heartfelt love and that no further evidence need be provided to make the case.