Lore in the publishing field says that in a bookstore, four seconds is about the maximum time in which a book can attract attention. If that musters interest, the shopper may open the book, or maybe decide right then and there to buy it. Likewise, the interior design decisions are territory belonging to the publisher. A book aimed at a senior citizen market would not do well with a small-sized type face. Nor would a book aimed at young children.
Some type faces are more appropriate to some topics than others.
Just look at any number of advertisements and try to imagine what they would look like with different type. Try reading something all in capital letters. The same holds for illustrations. In Dark Sky, Dark Land the author was proposing the use of a number of photos, mainly snapshots. The quality of the pictures varied widely.