You're right - right now it's basically a nicer version of getbootstrap.com/customize, with two extras:

- You can run it locally (or incorporate it into a NodeJS project) so that making changes in the UI changes a local bootstrap.css. No need to download or copy/paste styles, recompile LESS, etc

- User-generated Extensions. Third parties can add bits of LESS that you can incorporate to do things like re-style buttons and alerts, or add new components

I also have an open bug to incorporate pre-built bootswatch themes: https://github.com/bobby-brennan/strapping/issues

This was also a bit of an inspiration: http://bootstrap-live-customizer.com/