I’m an author, and with every project I start, I have at least three documents that contain information I need to refer to. Having those on a tabbed interface is perfect for me, then I can switch between them really easily. The little windows on the taskbar are far more inconvenient.
A tabbed interface can be set to not operate at all, or to show only when there is more than one document open. Since they’re open anyway, adding a more convenient way to switch between documents wouldn’t add much.