Tolkien had strong opinions on it. He regretted the attempts in the Hobbit to talk down to children and condemned all such approaches, including versions of old tales that removed the unseemly parts. There is an entire section on the topic in his essay, On Fairy Stories.

Let us not divide the human race into Eloi and Morlocks: pretty children - 'elves' as the eighteenth century often idiotically called them - with their fairytales (carefully pruned), and dark Morlocks tending their machines. If fairy-story as a kind is worth reading at all it is worthy to be written for and read by adults.

Also, he says the following. Remember that Tolkien served in WWI, losing most of his friends and his unit, and he says that during the war is when he became deeply interested, as an adult, in 'fairy stories':

If adults are to read fairy-stories as a natural branch of literature ... what are the values and functions of this kind? ... First of all: if written with art, the prime value of fairy-stories will simply be that value which, as literature, they share with other literary forms. But fairy-stories offer also, in a peculiar degree or mode, these things: Fantasy, Recovery, Escape, Consolation, all things of which children have, as a rule, less need than older people.