Ryan Dawson asks about the long-term viability of DataTemplate  http://www.longhornblogs.com/rdawson/archive/2005/10/08/14825.aspx

The best answer I can give is that the Sparkle UI is practically made of DataTemplates.  The DataTemplate is one of the most powerful and innovative concepts in WPF, but it takes some time to understand all the consequences and best practices. 

To be clear: If you don't want to use them, you don't have to.  Don't be afraid that if you're not using Model/View/ViewModel and DataTemplates you're doing something wrong.  Avalon is perfectly happy letting you build UI in a classic mode like you would with MFC or WinForms.  But I think you will find considerable productivity gains from using the new concepts.  And then you'll be hooked...