The Genesis Framework creates a stable, unchanging layer to your website that allows you to never worry about your Genesis compatible themes breaking due to a WordPress update. In my experience, retired themes are a major source of unexpected costs. This simply doesn’t happen when you use the Genesis Framework.
If WordPress is your website’s engine, then the Genesis Framework is your website’s chassis and body. The Genesis Framework sits directly on top of WordPress and is designed in such a way that you can picture it as having two sides. The inside, the side that touches WordPress, is updated when necessary. The outside, the side that your themes attach to, never changes.
Continuing with the car metaphor, StudioPress’ Genesis themes are your website’s paintjob and detailing. Because Genesis themes are applied to the framework rather than directly to WordPress, updates to WordPress don’t affect your theme. In fact, if the need ever arose to rebuild the framework from the ground up, as long as the outside layer is consistent, your theme still wouldn’t need to be updated.
This is in stark contrast to many free and professional themes that do not use a framework, instead hooking directly into WordPress and needing to be updated as WordPress updates. As WordPress continues to update, the code for these themes mutates until the developers decide that their code has become so convoluted that its more cost effective to retire the old theme and create a brand new one. Which of course leaves you with either a broken theme, or unable to update WordPress for fear of your site going down while you go thru the process of finding and applying a new theme and rebuilding your website.