For most of their existence, SFF novellas have been trapped in monthly magazines and anthologies, where only a fringe readership could visit them (along with short stories, but those babies can also live free in dedicated collections). At least, until Tor.com Publishing came along and liberated the novella, putting slender volumes in the hands of readers everywhere. In four years, they’ve published on the order of 100 and seem to announce new ones weekly, from a catholic stable of worthy practitioners. In 2016, capitalizing on the surge, Saga Press published the collected novellas of Ursula K. Le Guin. Last year, my local indie bookstore started populating a whole shelf with “Sci-Fi Novellas We Love.” All of a sudden, it was hip to be spare.
The form, after all, honors the genre: The novella traces its origins to fairytales and morality plays. Proto-fantasies, basically. In that sense, Tolkien’s world-building was never native to the genre. He simply blew up the balloon.
A balloon which is now about to burst. More than ever, successful world-building seems to require of creators a transmedia commitment to spin-offs and prequels and various other increasingly extraneous tie-ins like comic books and card games. Consumers are rightly overwhelmed. The joy of the sci-fi novella, by contrast, is in its one-off-ness, its collapsed space, its enforced incapaciousness. Authors can’t indulge family trees or maps; they must purify their storytelling. One or two main characters. A single three-act quest. Stark, sensible rules.
— Jason Kehe, “The Rise of the Sci-Fi Novella: All the Imagination, None of the Burden”, wired.com