This is not to say, of course, that Tolkien did not value the use of "distant time." His entire mythology is set to appear as "distant time." I think what he disliked was any distraction that would lessen the verisimilitude of what he was creating. It was vital to create a "suspension of disbelief" or "secondary belief" as Tolkien called it. Unbelievable machines distract from the appearance of reality. C S Lewis was criticized for the technical aspects of his spacecraft in the "Ransom Trilogy." (Perelandra, etc.) However, Lewis argues (in "Of Other Worlds," I think -- am am unable to locate the passage at present) that this technical problem is not too much of a distraction. These minor "technical difficulties" are usually easily overcome if the main story is "believable." Take the "Star Trek" stories, for example. We all know that the chronology conflicts with what actually has happened as we have entered the 21st Century, but the "suspension of belief" still works well in many of the episodes/movies/books -- in some of the stories much better than in others.
On the other hand, SciFi shows such as "Lost in Space" prove to be no more that just a diversion rather than a serious challenge to our "suspension of belief." The fact that we were not even close to sending passengers to other star systems by the turn of the 21st Century is less of a distraction than the plot lines (or lack thereof)! I admit that "Lost in Space" (or "Batman", for that matter) held my attention as a child, but such shows are mere nostalgic amusement for me today. There is too little plot and too many "preposterous and incredible" technical distractions. As C S Lewis put it: "I am almost inclined to set it up as a canon that a children's story which is enjoyed only by children is a bad children's story. The good ones last." ("On Three Way of Writing for Children" reprinted in the One-Volume Harper Collins The Chronicles of Narnia 2001, p. 771)
The Chronicles of Narnia have met the test of time -- people who enjoyed them as children still do as adults -- at least those who have not gotten so cynical or self-absorbed that they now think the stories foolish. Or have decided like the Bookstores that they belong only in the children's section, and that they are "beyond that." But as Lewis points out ("Three Ways", p.772), growth does not necessarily mean that you give up what you previously enjoyed. "Grown up" books can be added to one's reading without giving up what was enjoyed in childhood. "To be concerned about being grown up ... to blush at the suspicion of being childish; these things are the marks of childhood and adolescence. ... When I became a man I put away childish things, including the fear of childishness and the desire to be very grown up." (p. 771)
Unlike The Hobbit, The Lord of the Rings has been viewed as a more "adult" book, apparently "qualifying" it for the SciFi category. Which seems strange, given all the "juvenile" Science Fiction which has been written. But perhaps the designation is more of a "throw-back" to a time when "Fantasy" was not considered a category, especially for "grown up" books.
However you categorize the works of Tolkien and Lewis, what is the appeal of these "Other Worldly" stories? I think it is the appeal of most Fantasy and Science Fiction -- the desire for something "other." There is something in us that seeks beyond what we can see and touch and feel. Whether is is satisfied by a "historical narrative" (The Lord of the Rings), or through a mechanical (or magical) device (The Chronicles of Narnia and the Space Trilogy), or through a more "mystical" means (Smith of Wootton Major) does not seem to matter. We are transported through the suspension of belief into another world, which helps us (or can help us) to appreciate the world we live in every day. Some claim that such stories give us a false impression of the world. But the opposite seems to be more the truth:
[Fantasy] is accused of giving children a false impression of the world they live
in. But I think no literature that children could read gives them less of a
false impression. I think what profess to be realistic stories for children are
far more likely to deceive them. I never expected the real world to be like the
fairy tales. I think that I did expect school to be like the school stories. The
fantasies did not deceive me; the school stories did.
In a sense a child does not long for fairy land as a boy longs to be the hero of the first
eleven. Does anyone suppose he really longs for ... dragons in contemporary
England? I would be much truer to say that fairy land arouses him (to his
life-long enrichment) with the dim sense of something beyond his reach and, far
from dulling of emptying the actual world, gives it a new dimension of depth. He
does not despise real woods because he has read of enchanted woods: the reading
makes all woods enchanted. This is a special kind of longing. ... the boy reading a
fairy tale desires and is happy in the very fact of desiring. For his mind has
not been concentrated on himself, as it often is in the more realistic story. ("Three Ways" pp.774-75)
The use of fantasy and the "suspension of belief" can be very powerful, and dangerous in "the wrong hands." In Lewis's Introduction to his George MacDonald Anthology, he points to a time in his life where he was enamored with Romanticism and was in danger of floundering "into its darker and more evil forms." He sensed there was something different about MacDonald, but had no idea it was his Christianity coming through.
May God always turn your calamities into eucatastrophies,
The quality which had enchanted me in his imaginative works turned out to be
the quality of the real universe, the divine, magical, terrifying and ecstatic
reality in which we all live. ...what I learned to love in Phantestes was goodness. But now that I know, I see there was no deception. The
deception is all the other way around--in that prosaic moralism which confines
goodness to the region of Law and Duty, which never lets us feel the sweet air
blowing form 'the land of righteousness' ... (reprinted in the 1962 Edition of Phantastes and Lilith, (Gollancz) pp. 10-11)