One of the things I like most about the concept of the tablets is that they use well-established desktop technologies (such as GTK). End users dont care about this, but it makes it easier to bring already existing applications to the tablets without re-writing too much.

Breaking with well-established concepts might (not necessarily has to, but there's a risk) cause incompatibilities here. Its not that thousands of developers work on 3rd party apps for the tablets right now, right? I wonder if this number would further decrease if completely new UI-concepts would require devs to re-learn everything from scratch and make it harder (or impossible) to port desktop-application to the tablets.