Well, I already know that myelin is a fatty substance that coats some axons and protects them from interference from other neurons. However, I don't think that my definition is very well worded!
Also, from what I gathered (mainly from the Oxford Psych textbook and here) - I know that the role of myelin is to protect and insulate neurons, it also aids the transmission of impulses from one neuron to the next.
Therefore, I'm assuming the formation of myelin (myelination) is important because it allows the brain's signals to propagate faster and with less signal loss. In other words, myelin enables the transmission of signals between neurons to speed up, which can lead to further brain specialization.
Am I right? I don't think I have actually addressed the question of why myelin is so important.
How could I improve this answer if it were to appear in the exam?