A good image will draw people in to read your blog posts, making them more engaging. On the other hand, imagine going to a blog page with ten post excerpts and seeing a wall of words, broken up by the ten post titles. I’d have to be really motivated to dive into read those posts.
Images at the start of a post, make it easy for your readers to begin reading. As a bonus, social media updates with images get twice as much action as those without one.