Literary terms for graphic elements

An issue identified early in my research was that reviews of books with integrated graphic elements never really discuss how these elements are being used (if they even mentioned them at all). There are of course exceptions, in particular reviews in design publications like Eye magazine or Print, but for the most part I found two types of description: 'gimmicky' or 'whimsical'. A very rough explanation of these two categories is that 'gimmicky' voices disdain toward the graphic elements (why are there pictures meaninglessly interrupting the words?), where as 'whimsical' voices an appreciation of the graphic elements (there are these lovely little additions). However, neither actual address HOW the graphic elements are being employed. Why is there such a hesitance to discuss the visual? Is it because the reviewer doesn't consider the elements essential (in the case of the 'gimmicky', yes)? Or because a reviewer would rarely describe an author's use of alliteration, allegory or aside (as John Dale pointed out, literary devices are discussed in writing theory/workshop classes, not by your average reader)? Or is it because reviewers are by and large "word" people, an not comfortable with a vocabulary to discuss image? Margo Hammond illuminates this point when describing how graphic novels are reviewed (not exactly what I'm talking about, but the same problem):

"But perhaps the biggest obstacle to reviewing these works is that they are neither fish (totally text) nor fowl (totally art). There are very few of us who know how to review this genre. Even when we do address works like "Persepolis" and "Maus," it is the text that is usually examined most closely, with commentary on the artwork brought in as an afterthought. What should be considered, it seems to me, is the interplay between the two art forms, which lies at the heart of why these works differ from any other." (2004, 'Comic books for big people', http://www.poynter.org/profile/profile.asp?user=4399)

I've set myself the task of writing up book reviews of several relevant novels using literary terms to describe how the graphic elements are integrated into the narrative. Off the top of my head, I expect to find examples of chapter head illustrations used as foreshadowing (I have done this in some text designs recently), photographs/illustration as dramatic irony (the reader is shown something the protagonist isn't), photographs for flashback. Hopefully this will show that graphic elements can be described in the same terms as literary devices.