This is a fine way to work. I, for one, love SLIME. However, the main goal of Emacsy is not to load code at runtime; it's to be able to modify the UI of your application at runtime while providing some Emacs-like facilities.
Certainly, the normal way of embracing an application with Emacs is to turn Emacs into your frontend as you suggest. That works well for a number of applications, but it's not something you can distribute as a complete application, instead you might include your-app.el and hope for the best. Emacsy provides a way for you to improve your actual applications UI. Moreover, it allows your users to modify the UI to suit themselves.
Certainly, the normal way of embracing an application with Emacs is to turn Emacs into your frontend as you suggest. That works well for a number of applications, but it's not something you can distribute as a complete application, instead you might include your-app.el and hope for the best. Emacsy provides a way for you to improve your actual applications UI. Moreover, it allows your users to modify the UI to suit themselves.