Again Okonkwo mentions that Ezinma should have been a boy. Why is it important that he mentions this at this point in the story?

Ezinma has the spirit of the kind of boy that Okonkwo wants. The irony is that he has just killed his adopted son which had these same qualities. Okonkwo is really lamenting his own self destruction. He can only find the qualities of "manliness" in a girl. Okonkwo despises much about girls at the same time he kills his son Ikemefuna who could have been the salvation, in his eyes, for his eldest son Nwoye.