Albert Einstein famously said that "imagination is more important than knowledge." What he meant is that if we are ever to discover anything, we first have to elaborate an hypothesis to test out, and that process relies on imagination. Additionally, what we know as a fact may change as soon as evidence shows otherwise, so knowledge is little more than a useful tool to be used as a stepping stone for our abstractions.
If the most famous scientist of our age notoriously defended the importance of creative thought in scientific research, how ridiculously biased is the prejudice that sees "genre literature" (scifi and fantasy, above all) treated as second class, in comparison to more realistic and mundane settings?
The inconsistency of this bias is highlighted by the numerous undisputed classics that are heavily reliant on fantasy elements: from Ovid to Kafka or from Dante to Saint-Exupery, it's in the nature of art and the artist to attempt to add or show hidden meanings of everyday life. A universal context that can appeal to everyone as a human may well be found in a fictional universe designed for that purpose.
J.R.R. Tolkien famously wrote about how a world with a dragon was intrinsically more beautiful than a world without one:
“I desired dragons with a profound desire [...] Of course, I in my timid body did not wish to have them in the neighborhood. But the world that contained even the imagination of Fafnir was richer and more beautiful, at whatever cost of peril.”
Attachment to our known reality and its rules is also at odds with contemporary scientific theories: if the Universe is infinite (or there are multiple, possibly infinite universes), then everything and anything we can ever imagine must exist. Middle Earth and Westeros are just as real as we are, and in galaxy far, far away, epic battles are being fought with lightsabers.
Jumping back to Einstein and Tolkien, modern scientific theory can today make us hypothesize what humans have always understood through their intuition; the fantastical elements of myth and stories are not merely evasion, or decoration, and the absence of dragons in our daily lives doesn't make them less real in our minds and hearts.
The Romantic poet Keats explains the eternal and universal value of ancient Greek myth most elegantly in his "Ode on a Grecian Urn":
Heard melodies are sweet, but those unheard
Are sweeter: therefore, ye soft pipes, play on;
Not to the sensual ear, but, more endear’d,
Pipe to the spirit ditties of no tone:
Fair youth, beneath the trees, thou canst not leave
Thy song, nor ever can those trees be bare;
Bold lover, never, never canst thou kiss,
Though winning near the goal—yet, do not grieve;
She cannot fade, though thou hast not thy bliss,
For ever wilt thou love, and she be fair!
[...] “Beauty is truth, truth beauty,”—that is all
Ye know on earth, and all ye need to know.
Fantasy and science fiction are popular genres to this day because, just like modern day myths, they allow our imagination to build new worlds, think of new scenarios and solutions, through a process of abstraction from the limits and bonds of our everyday experience.
Star Trek is the embodiment of how the depiction of a Utopian future paved the way for both technological and social advancement in the very world we live in. Star Wars, The Lord of the Rings, Harry Potter, and Game of Thrones are solidly entrenched in popular culture. Yet Tolkien was quickly rejected when C.S. Lewis submitted his work for the Nobel Prize, and in 2016 songwriter Bob Dylan was mysteriously considered worthier of the prize than any other novelist (including J.K. Rowling, who sold more than 400 million copies of her books worldwide).
I confess, I do write science fiction (you can find my first novel, Julia Dream, here); I don't expect the Nobel Prize, but I don’t identify my work as “paraliterature” either.