Same problem here. The admin site structure of the typical CMS is an abstraction that makes obvious sense to us developers, but not necessarily to the content managers. Inline is the future.
Couldn't agree more. For the past year or so I've been building sites for clients using Concrete5 (an open source php CMS), and it has this concept at its core -- you edit the site on the actual pages themselves, which much more closely matches the mental model of non-technical users. Furthermore, it provides a lot of flexibility for the developer to customize the editing interface -- you edit content as smaller "blocks" on a page instead of one monolithic WYSIWYG editor for the entire page. In this way, you can have a small little custom interface specifically tailored to that one spot on the page.
It's a really elegant system that is unfortunately not as well documented as it could be (I'm hoping to do something about this in the near future though), and since it's a relative newcomer to the php CMS world (open-sourced in 2007 or 2008?), it doesn't have as much name recognition as Wordpress/Joomla/Drupal.
But as you point out, inline is the future, and C5 is way more mature than any other similar CMS I've seen, so I think it's an ideal solution for many CMS needs.
Most of the expensive CMS products have edit in place, so a user can just click and edit. This does come with quite a large overhead in pageweight in my experience.