Pardon my asking, but wouldn't a sizeable chunk of the Star Wars be classified as Sci-Fi Romance?
In any case, romance not being truly a genre (it's a plot), sci-fi romance is neither revolutionary, nor deserving of its own category (in my humble opinion).
Historical, contemporary, fantasy and other types of romance novels having already been done to death, it really is a wonder why sci-fi romance, with all its possibilities (a handsome three-tongued Alien prince, leading an armada of spaceships on a mission to conquer Earth, loses his heart to a beautiful earthling) has not yet been explored to the fullest.
Which brings me to another thought (bear with me, it does happen rather infrequently). Should we, as writers, make an effort to distinguish between a plot and a genre in general?
To me, the word genre has always been close in meaning to the word medium. Genre describes the WORLD in which our story takes place - be it 16th century Italy, 23d century Mars, or an undated goblin kingdom. It says nothing of the events that are to happen in our world, says nothing of the story, or the conflict therein. All of these are the domain of the plot.
As such, I would not classify romance or mystery or horror as genres. They're all plots. Why should we be careful to make this distinction?
Frankly, I believe that often, not realizing that, say, mystery or horror are plots, not genres, science fiction writers have a tendency to limit themselves (subconsciously, perhaps) to the linear adventure plot as the only one acceptable in science fiction. As a result we're missing out on many great sci-fi mysteries, sci-fi romances, and sci-fi horror stories.
In short, science fiction romance is NOT a combination of genres. It is a welcome enrichment of a genre with a rarely-used plot. The better we remember it, the more varied our stories will be.