Answer:
The poet most likely includes this allusion to help show that books were a source of comfort and imagination for the speaker.
Explanation:
The speaker of "A Poem for My Librarian, Mrs. Long", by Nikki Giovanni, is reminiscing about when she was younger. Back then, when there was no possibility of watching TV all the time, she delighted herself in reading books. Books are still something the speaker loves (hardcover being the preference), something that opens the door to a different world, just like the wardrobe did in "Chronicles of Narnia". However, the speaker feels safe, comforted/comfortable in this new world. Unlike the children who crossed to Narnia to find witches and lions, war and challenges, she found only happiness:
And Mrs. Long opened that wardrobe
But no lions or witches scared me
I went through
Knowing there would be
Spring
