Because it would mean creating a situation where they meet these creatures, and as a general rule you can't jump genres from science fiction to fantasy. High technology and magic just don't mix.
So no, in my opinion it would make no sense whatsoever.
???
Have you never read anything by Joan D. Vinge? Neil Gaiman? Garth Nix? Neil Shusterman?
Ursula K. LeGuin?
Isaac Bloody Asimov???
Sci-Fi and Fantasy are among the most frequently crossed genres in the publishing industry!!
(I should know; I've read most of it.)
Anyway, it might have been plausible if they invented a collective Time Matrix-built universe, but ONLY then.
Only Gaiman, and everything I've read by him has fallen distinctly into the 'fantasy' category. I am aware of the works of Asimov, but was not aware of any magical creatures in his books.
Science fiction is a bit of a woolly term anyway, since any book with aliens and spaceships is branded science fiction despite often having little or no scientific basis. By this logic fantasy is a more appropriate term, the morphing technology for example may as well be magic as it is given no basis in science. I think the term Sci-fi/ fantasy is used a lot for that reason
Although to clarify my original point I meant that science fiction (as in aliens and spaceships) and fantasy (magic, wizards, unicorns etc) do not mix, especially when you have a series that was based in a world of alien races and high technology.
To suddenly have phoenixes and unicorns (creatures with magical powers) turn up would be to suddenly say 'magic is real'.
Hopefully that has clarified my point and hasn't dug me into an even deeper hole.
To go on further, we need to cover the concepts of "low sci-fi/fantasy" and "high sci-fi fantasy".
Let's say what Wikipedia has to say about this-
High fantasy, or epic fantasy, is a subgenre of fantasy fiction that is set in invented or parallel worlds. Built upon the platform of a diverse body of works in the already very popular fantasy genre, high fantasy came to fruition through the work of authors such as C. S. Lewis and, foremost, J. R. R. Tolkien, whose major fantasy works were published in the 1950s. While it is far from being the oldest fantasy subgenre, high fantasy, along with sword and sorcery, has become one of the two genres most commonly associated with the general term fantasy.
Hard science fiction is a category of science fiction characterized by an emphasis on scientific or technical detail, or on scientific accuracy, or on both.[1][2] The term was first used in print in 1957 by P. Schuyler Miller in a review of John W. Campbell, Jr.'s Islands of Space in Astounding Science Fiction.[3][4][5] The complementary term soft science fiction (formed by analogy to "hard science fiction"[6]) first appeared in the late 1970s as a way of describing science fiction in which science is not featured, or violates the scientific understanding at the time of writing.
The term sometimes also contrasts the "hardness" of the sciences used in the story: the "hard" sciences are quantitative or material-based disciplines, such as physics, chemistry, biology, and astronomy; while the more "soft" sciences are social sciences, such as sociology, anthropology, or psychology. Stories featuring engineering tend to be categorized as hard SF, although technically engineering is not a science. Neither term is part of a rigorous taxonomy — instead they are rule-of-thumb ways of characterizing stories that reviewers and commentators have found useful. The categorization "hard SF" represents a position on a scale from "softer" to "harder", not a binary classification.
Low fantasy is an umbrella term, describing various works within different sub-genres of fantasy, to contrast specific works with high fantasy. Though a very vague term, features that may indicate low fantasy downplaying of epic or dramatic aspects; includes de-emphasising magic; real-world settings; favoring of realism, cynical storytelling; and dark fantasy. The archetypal example of low fantasy would be a story taking place in a quasi-historical setting where the protagonists lack a clear moral initiative and might be haunted or driven by a dark past or character flaw, and where conventional fantasy elements such as magic, elves, or dwarves are lacking or are absent.
There are many arguments about what constitutes the line between Low and High fantasy, but invariably in High Fantasy there is a moral dichotomy of altruistic good and unredeemable evil, and in low fantasy there are many shades of gray, where the "main character" is often an anti-hero. For instance, immoral elves or mercenary dwarves could commonly appear in a low fantasy tale, but rarely in high fantasy.
The Lord of the Rings is seen as the quintessential high fantasy tale that all others either emulate or studiously avoid, and so elves and dwarves and a commonality of magic are seen as the hallmarks of High Fantasy, but in truth it is the stark black and white separation of good and evil that locks it into the "High Fantasy" realm. Shadowrun, and the lore behind Shadowbane, are both examples of fantasy that includes elves and dwarves, in a setting without a clear good/evil dichotomy. Many of the White Wolf role-playing games would also be considered low fantasy, while including magic and/or "fantastical" races and themes because of the moral ambiguity of the setting. Additionally, Star Wars lacks typical High Fantasy races and has a sci-fi setting, yet maintains the High Fantasy good v. evil theme.
The Sword and Sorcery genre is the the style of fantasy writing most associated with Low Fantasy.
Soft science fiction, or soft SF, like its complementary opposite hard science fiction, is a descriptive term that points to the role and nature of the science content in a science fiction story. The term first appeared in the late 1970s and early 1980s and indicated SF based not on engineering or the "hard" sciences (for example, physics, astronomy, or chemistry) but on the "soft" sciences, and especially the social sciences (anthropology, sociology, psychology, political science, and so on).[1] Another sense is SF that is more concerned with character, society, or other speculative ideas and themes that are not centrally tied to scientific or engineering speculations. A third sense is SF that is less rigorous in its application of scientific ideas, for example allowing faster-than-light space travel in a setting that otherwise follows more conservative standards.
A fantasy morph MM5 would work with low fantasy/soft sci-fi; Animorphs already is pretty much soft scif-fi.