Interesting solution but it should be a plugin. Simplifying the admin area is a good lead but as referred by expert-a risky ordeal. Because if I want to setup a church or a school site, I should just have church or school features in place rather than the whole options. But since WP devs are not particular to making plugins for mainstream/niche sites/business without activating a whole lot of plugins which bring about several training before the site is given to the owners, then this should be a good lead. But can work to deactivate the admin with an option to activate it anytime and allow the plugin to take control the admin features management.