And for adults, the world of fantasy books returns to us the great words of power which, in order to be tamed, we have excised from our adult vocabularies. These words are the pornography of innocence, words which adults no longer use with other adults, and so we laugh at them and consign them to the nursery, fear masking as cynicism. These are the words that were forged in the earth, air, fire, and water of human existence, and the words are:
Love. Hate. Good. Evil. Courage. Honor. Truth.
— Jane Yolen, Touch Magic: Fantasy, Faerie & Folklore in the Literature of Childhood
Perhaps in the process of making a work of fantasy "adult", you end up robbing it of some of its potential power.