WinRT solves many of the problems of Win32, from an apps perspective, though it can't be used for certain things of course (writing NT services, drivers, and the like). Apps created for WinRT are safe, secure, and sandboxed, can't wreck other apps, can't cause "Windows rot," and all install in just 2-3 seconds. They feature isolated storage, single folder installs (as per the Mac), and require user consent to access the general file system. When Microsoft says it "reimagined" every aspect of Windows, this new runtime, or application model, must be included as well. This is part of it, a modern, truly different app platform that is far more different, and far more capable, than many people understand right now.
And in the same vein of blowing past peoples' expectations, virtually no app could not be written as a WinRT app. Many are imagining very simple, HTML-like apps, and while I'm sure there will be plenty of those, you need to reset your expectations up. WinRT is amazingly full-featured and not constrained to goofy utilities and simple games. The next "Call of Duty" could be a WinRT app, complete with support for Edge UIs and Charms.
And you laughed when they repeated "Windows reimagined over and over again in Tuesday's keynote. I'm starting to think they didn't push this point enough.