Warning: heavy generalizations follow. I know there are a few, a very few exceptions, but by and large, the following is, I believe, 99% spot-on:
Romance (genre) is like obscenity: you may find it hard to define, but you know it when you see it. Anything with naked torsos is suspect, and so is a romantic embrace cover, because we all know that's cover code for the Romance genre.
Setting is and has always been a subset of Romance, not vice versa. Historical romance is romance with a historical setting, not history with romance thrown in. Sci-fi romance is Romance with a sci-fi setting, not sci-fi with a romance thrown in etc. If it's science fiction with a romance in it, it's science fiction, not Romance. We all know it, and that's why this change needed to be made. Nearly nobody cruises the sci-fi category looking for any sort of Romance, because if they want Romance, they go to Romance categories.
Categories are there for a reason. The definitions are good for discovery, good for consumers. Miscategorizations help nobody. Arguing by extreme, if there were no categories, there would be almost no discovery. The more well-defined categories, the better for everyone.