If asked what the most powerful tool in shaping the future generation is, one could argue that children's literature plays a major role. From picture books to young adult novels, the words and images we infuse in our children's minds build their perception of the world, impact their emotional growth, and guide their moral compass. And a singularly crucial aspect of this is how emotions are portrayed and processed in these treasured tales.

Why is Emotion Important in Children's Literature?
At its core, children's literature serves to both educate and entertain young minds. Understanding and identifying emotions is a critical developmental milestone. By incorporating a broad spectrum of emotions - joy, sadness, anger, fear, and more - children's books can act as mirrors and windows, allowing children to relate to the characters' feelings, as well as understand others' emotional experiences.

The Evolution of Emotional Expression in Children's Books
Historically, children's literature painted a fairly pared-back, sometimes even stoic, image of emotional expression. However, in the past few decades, we’ve seen an encouraging shift. Books now cover complex emotions and difficult situations, and more importantly, model ways to navigate them healthily. This progression sends an integral message to children: It's normal and okay to experience a myriad of emotions.

Emotions as Storytelling Tools
Emotion doesn’t merely enrich the content of children’s books; it serves as a critical storytelling tool. It’s utilized to form deeper connections between the readers and the characters. We root for the characters when they're happy, feel for them when they're sad, and sometimes even share their anger. It's this emotional rollercoaster that makes a story unforgettable.

The Impact on Children's Emotional Development
Study after study has shown the favorable impact of emotive literature on children’s emotional intelligence. By providing a safe space to explore and navigate various emotions, children's literature can help youngsters understand and manage their feelings more effectively. This includes empathy too, fostering them to be more compassionate and to support their peers’ emotional journeys.

The Role of Parents and Teachers
The role of the adult is crucial in mediating the impact of emotional content. In reading to or with children, adults should encourage discussions about the emotions encountered in the tale. This practice helps children internalize the nuances and validate their feelings, ultimately nurturing a greater emotional awareness.

Whether it's the palpable fear felt by Harry Potter standing up to Voldemort or the unconditional love that radiates from the family in 'Little Women', the emotional quotient in children’s literature is a powerful tool in shaping young hearts and minds. As more authors embrace the psychological depth in their storytelling, the future promises an exciting landscape of emotive children's literature.

Remember, a book is not just a book. It's a mirror reflecting us, and a window to others. In each book, lies a unique journey of emotions just waiting to be discovered.