I think to put a modern spin on this is kind of unnecessary. One of the things that makes Superman distinctive is that his character is derived from the Golden Age. If you think of the modern amenities available now - microwave ovens, interstate highways, cell phones - none of those existed back then and so the character is inherently rooted in the pulpy science fiction novels of the 1930s, or to go back even further to Verne or Burroughs. Just like we don't try to rationalize how the Nautilus might have been possible in the 1800s, we sort of need to take the inexplicable parts of Superman's origin as a legacy of the development of the medium. That considered though, such oversights like why there is only room for one does not detract very much away from the character in terms of origin. In the wide realm of explanations it still is a lot tighter than "can shoot lasers out of his eyes because of genetic evolution."
In both literature and human culture there is also the concept of the savior, but the solitary savior. Jesus acted alone, as did Mohammed, but so then too did characters from a lot of stories, for instance I Am Legend. If Superman had come with his whole family, it would have taken away from this concept, and made him less of a hero.