boutta ramble about fairy stories/fantasy in particular, though these ideas can be applied more broadly:
in 'on fairy-stories', tolkien disputes the idea that fairy stories are primarily for children. he argues that this approach 'produced a dreadful undergrowth of stories written or adapted to what was or is conceived to be the measure of children's minds and needs' -- taking fairy tales and 'mollifying' them to be more child-friendly.
he criticises these 'imitations' for being 'silly' and 'patronising', but his single biggest issue with these adaptations is that they are 'covertly sniggering, with ... an eye on the faces of other clever people over the heads of his child-audience'.
(there is a touch of this in the hobbit; the narrator occasionally makes jokey asides/anachronistic references to the reader, which does feel somewhat like tolkien winking at his adult audience. he wrote 'on fairy-stories' between the hobbit and the lord of the rings, and that ironic voice completely disappears in the latter, so he clearly put his own theory of fantasy into practice.)
this approach, firstly, does a disservice to the story as a work of fantasy fiction and refuses to let the writing stand for itself. it's as if the author doesn't trust their own secondary world to stand up under scrutiny, so, before any of their readers have the chance to criticise it, they rush in to say: 'oh, by the way, i know how silly this sounds. i'm aware of it, and therefore this silliness isn't a flaw within the world that i've built.'
but secondly. damn. literature (and art in general) is supposed to introduce us to new ideas and help us to grow. it can't do that if it's too busy tripping over itself to show us how clever and ironic it is. 'say something true and real.' 'sorrryyyy i can't )): you see, my foot is in my mouth )):' die about it