There are three common ways of regarding the Fantasy genre of which Tolkien is prime exemplar: as escape, demonism or providing glimpses of Heaven.
1. Escape - the mainstream view, essentially secular and materialist.
Fantasy is contrasted with 'real life', fantasy is unreal, real life is meaningless, purposeless and alienation - so anyone who wants to spend time on Fantasy is trying to escape 'real life': a taste for fantasy is thus a sign of weakness, immaturity, refusal of responsibility.
Fantasy is un-reality.
2. Demonism - Christianity is truth, Fantasy is not the same as Christianity and contains themes (or words) related to scripturally-prohibited activities.
A taste for fantasy is therefore seen as either evidence of or tending to produce anti-Christianity.
(The Harry Potter series is often, but utterly mistakenly, regarded in this light; however, the criticism does sometimes apply.)
Fantasy is anti-reality.
3. Glimpses of Heaven - the view articulated by Tolkien in On Fairy Stories: that true fantasy is the successful attempt to write about Heaven rather than this earth ('real life') - but this can only be achieved very partially and imperfectly, and indirectly (as a sub-creation within the primary creation); in flashes, or hints, or reminders of what we already know and hope for ('eucatastrophe' is his word).
C.S Lewis sees this feeling as a natural yearning for Heaven and evidence that Heaven is 'real life' for Man.
Fantasy is reality.
So Fantasy, as a genre, can appear either irrelevant, evil, or one of the most important things on earth.