I'm just surprised we haven't seem some app that can act like a wordpress admin page but generating a static output you can host for free or very cheap somewhere.

First, the site generator is MIT licensed but I don't see a link to the license. If someone forks this generator, would they be in compliance with MIT license requirements?

Second, the images linked in this site are quite nice. I can imagine someone choosing to use some of them as is. Are they yours to share?

Third, it appears that you are targeting non-developers. I would think about how to make it as easy as possible to customize. Decisions like putting images in "priv/output/images" seems a bit confusing.