Working with XML is 'a piece of cake' for XML Experts, but the vast majority of Subject Matter Experts have no interest in learning or knowing anything about XML or the DITA standard for that matter. This is the reason that DITA Exchange comes with an editor for both groups of content contributors:

The Subject Matter Expert - with no knowledge about XML or DITA - can edit the topic in Word 2007 without any tagging or strange coding.

some SME's may be allowed to do in-line editing

other SME's (in a commenting role) may only be allowed to submit comments to the content.

The XML Expert can toggle to XML editing view and work with attributes, XML elements etc.

The XML Expert will always stay in control of the process, because the edits/comments submitted by the SME will be stored in a minor version of the topic.