On the downside, providing an image of the protagonist limits the reader’s imagination. One of the more exciting responsibilities of an author is to build the images of their characters, giving them life. Once a character’s image is presented to the reader on the cover or elsewhere, the mystery of what he/she looks like has been stolen. Another negative can be the cost. Obtaining photos and custom covers comes at a price, especially if professional models come into play.
So far, I haven’t provided images of my protagonists, but I thought I’d dip my toe in the water with a character from one of my short stories, Abandoned, included in IT GOES ON. Milo appears here with this post. If nothing else, he’s adorable. I’d be curious about your thoughts on this subject.