Soka Gakkai leaders are jealous of Shakyamuni Buddha. They should have infinite gratitude to him as did Nichiren.

"All the True Word priests go through a secret ceremony of anointment, in which pictures of Shakyamuni Buddha and others are painted on an eight-petaled lotus and the participants tread on them with their feet. And because those who took part in this bizarre ritual were revered and treated as the supervisors of various temples by the Retired Emperor of Oki, power passed into the hands of his common subjects, and he met with disgrace in this life." -- Repaying Debts of Gratitude

Soka Gakkai leaders hate Shakyamuni Buddha for the same reason Shingon believers hate Shakyamuni Buddha...jealousy. There is no comparison between Shakyamuni Buddha and the principle Buddhas of Shingon and Soka Gakkai (Vairochaina for Shingon and Daisaku Ikeda for Soka Gakkai). Shakyamuni Buddha far outshines Vairochaina Buddha and Daisaku Ikeda. 

Soka Gakkai members may declare, "we are equal to Shakyamuni Buddha by the principle, “At the start I took a vow, hoping to make all persons equal to me, without any distinction between us, and what I long ago hoped for has now been fulfilled.” -- Lotus Sutra Chapter 2 and they may also site the following from the True Object of Worship

"With full understanding of Shakyamuni’s teachings, the four great voice-hearers said, 'This cluster of unsurpassed jewels has come to us unsought.' They represent the world of the voice-hearer that is within ourselves. The Buddha stated, 'At the start I took a vow, hoping to make all persons equal to me, without any distinction between us, and what I long ago hoped for has now been fulfilled. I have converted all living beings and caused them all to enter the Buddha way.' Shakyamuni Buddha, who has attained perfect enlightenment, is our own flesh and blood. His practices and the resulting virtues are our bones and marrow. The “Treasure Tower” chapter of the Lotus Sutra says, “He who is capable of guarding the Law of this sutra will thereby have offered alms to me and to Many Treasures.... One who guards this sutra will also have offered alms to the emanation Buddhas who have come here adorning and making brilliant all the various worlds.” Shakyamuni, Many Treasures, and the Buddhas of the ten directions represent the world of Buddhahood within ourselves. By searching them out within us, we can receive the benefits of all these Buddhas. This is what is meant by the following passage: “If one listens to them [the preachers of the Law] for even a moment, one will immediately attain supreme perfect enlightenment.” The “Life Span” chapter reads, “It has been immeasurable, boundless hundreds, thousands, ten thousands, millions of nayutas of kalpas since I in fact attained Buddhahood.” The Shakyamuni Buddha within our lives is the eternal Buddha since time without beginning, who obtained the three bodies more than numberless major world system dust particle kalpas ago. The “Life Span” chapter states, “Originally I practiced the bodhisattva way, and the life span that I acquired then has yet to come to an end but will last twice the number of years that have already passed.” He was speaking of the world of the bodhisattva within ourselves. The bodhisattvas, as numerous as the dust particles of a thousand worlds who emerged from beneath the earth, are the followers of the Shakyamuni Buddha present in our lives. They follow the Buddha just as T’ai-kung Wang and Tan, the Duke of Chou, served as ministers to King Wu of the Chou dynasty and later assisted his son and successor, the infant King Ch’eng; or just as the Chief Minister Takenouchi supported Empress Jingū and later her grandson Crown Prince Nintoku as a highly valued minister. The bodhisattvas Superior Practices, Boundless Practices, Pure Practices, and Firmly Established Practices represent the world of the bodhisattvawithin ourselves. The Great Teacher Miao-lo says: 'You should understand that one’s life and its environment at a single moment encompass the three thousand realms. Therefore, when one attains the Buddha way, one puts oneself in accord with this fundamental principle, and one’s body and mind at a single moment pervade the entire realm of phenomena.

First, at his place of enlightenment, Shakyamuni Buddha [preached the Flower Garland Sutra in which he] revealed the Lotus Treasury World. In the following fifty years, until he entered nirvana in the grove of sal trees, Shakyamuni preached about the lands of the various Buddhas, such as the Lotus Treasury World and the Land of Secret Solemnity [in the Secret Solemnity Sutra], revealed the three kinds of lands when he three times purified countless lands [in the theoretical teaching of the Lotus Sutra], and revealed the four kinds of landsaccording to the four different views [in the Nirvana Sutra]. These lands—the Land of Transition, the Land of Actual Reward, and the Land of Tranquil Light; the Land of Peace and Sustenance, the Pure Emerald World, the Land of Secret Solemnity, and the lands of all the other Buddhas—are transient lands that change in the course of the kalpas of formation, [continuance, decline, and disintegration]. The Buddhas of these lands had been magically conjured by Shakyamuni Buddha, and when the lord of teachings entered nirvana, all these Buddhas likewise entered extinction. In the same way, their lands also vanished.

The sahā world Shakyamuni Buddha revealed in the 'Life Span' chapter is the eternal pure land, impervious to the three calamities and to the cycle of the four kalpas. The Buddha neither has entered into extinction in the past nor will be born in the future. And the same is true of his disciples. This means that their lives are perfectly endowed with the three thousand worlds, that is, with the three realms of existence. The Buddha did not reveal this truth in the theoretical teaching, or the first fourteen chapters, of the Lotus Sutra because the time was not right and the people’s capacity was not yet developed.

Shakyamuni Buddha did not transmit the five characters of Namu-myoho-renge-kyo, the heart of the essential teaching of the Lotus Sutra, even to the bodhisattvas Manjushrī and Medicine King, let alone to any lesser disciples. He summoned from beneath the earth the great bodhisattvas as numerous as the dust particles of a thousand worlds and, as he preached the eight chapters, transferred it solely to them." -- Nichiren in the True Object of Worship

Even if we are equal to Shakyamuni Buddha, it is thanks to him that we are equal since he converted us in the infinite past. Therefore, we should have infinite gratitude to Shakyamuni Buddha, as did Nichiren, not disdain for Shakyamuni Buddha as in Shingon and Soka Gakkai.