After having written to her with my thoughts, I found two other answers to similar questions online, which I thought were worth sharing here.
This insight is from Hobie Hobart:
Is it ever a good idea to put your picture on a book cover?
This is contingent on many factors so the initial answer is, it depends. It IS a good idea, and nearly mandatory, to use your picture on the front cover if you are a Barack Obama, an Oprah, or a renowned superstar. Many authors think that putting their picture on the front cover will make them famous. This is not necessarily so. Unless you are well known in the media, bookstore buyers will not accept your book which pictures you on the front cover. However, if you are selling exclusively to a tight niche where you are well known, or your intention is to start branding yourself to a specific market, your photo on the front cover or the spine can be an advantage.
This is how Michele DeFilippo answered this question:
Should I put my own photo on my book cover?
It depends. If YOU are the product, then your picture can absolutely be used on the front cover (think Dr. Phil or Suze Orman). If your book is non-fiction, you are a well-known expert in your field, and buyers would recognize your face, then your picture can be used on the back cover, along with a bio. Otherwise, your picture and bio belong in the back matter of the book.
Ultimately the answer is, "It depends!" But often the answer is, "No." Think carefully about your market and your branding before deciding to put your photo on your book cover.