Visual stimulus vs. imagination

I'm always hesitant to apply too literal a visual interpretation of my books - both in covers and in the teasers/promos I put together. I don't like the idea of assigning an idea of what a character looks like when it should be up to the reader to fill in those blanks. 

This hesitation seems to be completely contradicted by the wealth of material out there suggesting this doesn't matter. The vast majority of book covers in the romance area feature photos to give you no doubt as to how the author sees their character(s). Those books obviously sell and don't seem to hinder the reader's acceptance of that visual. 

Given that, maybe I'm just someone who prefers to tease . . .