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.