This is my interpretation:
I agree, I think Space Fantasy is more accurate of what Star Wars is. The term Space Opera comes from the likes of shows like Flash Gordon, Lost in Space etc, where the story seems to go on and on and on… like a soap opera. And initially that was what I think George Lucas was trying to achieve. And then he seemed to abandoned it for a 9 episode saga where by the end of the 9th episode the Emperor would be destroyed. But of course by the completed script of Return of the Jedi he had decided to make ROTJ the final conclusion to the Saga. Now with the new movies Snoke was introduced to fill the role.