Number of writings on a topic may not speak to its importance

Lack of followers of a given background may be why they were not addressed in Tablets

"As there were no followers of the Bab or Baha'u'llah derived from the religions of the Far East in Their days, this may be the reason that They did not address any Tablets directly to these people. Also we must remember that every religion springs from some root, and just as Christianity sprang from Judaism, our own religion sprang from Islam, and that is why so many of the teachings deduce their proofs from Islam."

(Shoghi Effendi, 5 March 1957, Revised September 1990, in Buddha, Krishna, Zoroaster and Related Subjects, no. 25, in Lights of Guidance, no. 1695)

Number of Tablets to women enjoining them to teach is due to letters arriving in the Holy Land mostly coming from women

"As for the large number of Tablets addressed to women enjoining them to teach the Cause: since the letters arriving in the Holy Land come for the most part from women, and only rarely from men, it is natural that women should be written to more frequently than men...."

('Abdu'l-Bahá, extract from a Tablet of 'Abdu'l-Bahá, at https://bahai.org/library/authoritative-texts/abdul-baha/additional-tablets-extracts-talks/271134634/1#043188027 )