This plugin does exactly what it claims to do, which is add solid widgetized footer functionality to the Genesis framework. It allows users to change areas that otherwise require coding inside the child theme itself.
Now, some people have left 1 star reviews because Genesis is not free. The documentation states this clearly, but others have decided to ignore that and bash the author of the plugin instead.
There are many plugins in the repository that serve as add-ons to paid products. Some for other commercial themes (Thesis, Headway), Gravity Forms, and others for niche products that have a SaaS component that is not free. This is perfectly OK and shows that the WP ecosystem can work with commercial products.