Why such emphasis on personal guidance in the Soka Gakkai?

One reason is SGI members do not have a valid Gohonzon. Therefore, they have no way to tap into the guidance and encouragement of the Original Buddha Shakyamuni, Nichiren Daishonin, and the Law. Another reason is to create uniformity in thinking and behavior. Still another reason is that the SGI needs to reinforce the SGI way since not ALL their teachings are found in the Lotus Sutra and Writings of Nichiren, let alone the authenticated writings. Also, it is the carrot for the unpaid senior leader bee workers to feel important [power] since they aren't paid one red cent for their hard work.