Those of us who have read or watched science fiction know that one of the most common characteristics of sci-fi is travel through space. Star Wars, Star Trek, Dune, The Foundation Series, and the many of the most famous works of Arthur C. Clarke, Robert Heinlein, and other classic authors occur in space. Among modern sci-fi, award-winning books like Redshirts and Ancillary Justice also take place in this environment.
Space is, of course, beautiful, and has its charms, but I believe that the genre’s focus on space does not make much sense. Realistically speaking, it is unlikely we are ever going to be able to jump across stars in a single lifetime, and science fiction is about the future, or the possibilities of the future. Therefore, I believe that stories that take place in space, but lack realism — often, but not always, grouped together as “Space Opera” — are merely works of fantasy that take place in space. Even then, these works too ought to be subject to believable in-world explanations of why things are the way they are.