Administration can be no more than filling out forms, uploading images, etc, etc. No plugins, no DBs, no hosting, no nuthin'.
I raised the point in comments above, but there is a big different between creating a new page from scratch and using a simple form to create a templated page. WordPress (or any blogging tool) doesn't make you build your blog post as a page draggin modules onto it...they give you a special admin page where you just fill in the title and body text and click publish...what could be simpler?
In-context editing does work great for many use cases, but it doesn't work well for some. Think about when you need to create a slightly interactive web page...not just a simple static one. You'd like one section of the page to fade in/out when the user hovers over an image for instance...I haven't seen anyone pull off an in-context UI that makes that easy but I've seen some great form based UI's that make that 30 secs work for a non-technical user.
Check out the Carrington Build WordPress plugin (no affiliation) for a decent example of providing users with a very simple admin page builder drag and drop layout tool.
I do wholeheartedly agree that very few CMS tools have an awesome UI for business users...maybe you can change that.
Custom CMSs are the way to go (not customizable, like drupal: custom made). This is, for me, the biggest advantage of document databases. I'm new to software design, and self taught, but not a coder. I've never tangled with a relational database yet. It's incredibly easy to design case-specific CMSs with document databases.
It all boils down to form design.