The other side of the coin of asking “Why?” is, of course, “Why not?” Why did not the author include a particular topic which might have suited the text well? Here we will be treading a tricky path, as now we need to postulate hypotheses which might be alien to the text. Nevertheless, this task is certainly valid if we wanted to do comparative studies. For example, in Synoptic studies it is perfectly justifiable, indeed, advisable, to ask why Matthew omitted certain things which were included in Mark and vice versa. And that’s why I could appreciate better why Harvard Divinity School requires you to study two religious traditions (aside from its well known liberal outlook, naturally). Only by doing so you could free yourself from the entrapment of your own tradition. Not that every tradition is necessarily myopic, but being engrossed in your own tradition can be a narcissistic enterprise, indeed.
To apply the same question to the history of the church, we could then ask, why was the church silent about this or that topic during a certain era? What does, let say, the silent treatment of social justice say about the church at that time? I really think we could learn a lot of things not just from what is present from the text, but from what should be present from it but is absent now, although again a lot of subjectivity will play a huge factor here, as often we read what we want to read. A dialectical approach between asking “Why?” and “Why not?” will help, as each will strengthen the other, but it also can doom the whole process into utter speculative nonsense.