Our lives would be impoverished without positive emotions such as fun, pleasure, joy, excitement; but also middling emotions of satisfaction, calmness, boredom; even negative emotions such as anger, sadness, melancholy and fear. They are ever-present and part of what it is to be human.
One facet of Learning Experience Design is to make the effort to engage the learner by injecting emotion into the experience. This does not mean blind emotion. Over-stimulation can be a bad thing in learning. The right kind of emotion is what helps learning, as this affective dimension can motivate the learner and aid retention. It is a matter of designing for both head and heart. It would be fair to say that most of what is written about learning design has a focus on cognition and understanding, whereas much of what drives us is feeling and emotion.