WP Theme Preview Improvement

Hi
Not sure if this is the correct forum for this suggestion (not question) it would be nice though to get feedback.
Why doesn’t WordPress include basic dummy data on the same server that the themes are served. The few times i’ve looked through the available themes it always seems such a hit and miss exercise since we only get to ‘preview an empty template, thus relying on the thumbnail image. Would it take much to supply a preview of the theme with a few dummy posts and images and taxonomy entities tags, catgs etc … then we can properly assess the template as its meant to look?? As it is presently we’re usually looking at a near blank page … whats the point??