I've seen tons of themes that looked great in the screenshot and bland in the demo, e.g. because many of the special features were in front-page.php. And I could say that a theme meant for download should be at least somewhat generic and make the best out of any content it's given. Many themes eschew standard WP mechanisms in favor of custom code that has to be specifically catered to, and that's wrong. But the official demo content is also very bland; lack of featured images on posts (to use your example) is an obvious omission that would be easy to fix.