Joey Hess posted in Debian Tasksel:
This ensures that the desktop will fit on CD#1, which gnome currently does not. There may be other reasons to prefer xfce as the default as well, but that is a complex and subjective topic. Unfortunatly, Debian does not have a well-defined procedure for making such choices, though it certianly has well-defined procedures for reviewing them. So, I've decided to be bold, and continue the tradition of making an arbitrary desktop selection for Debian in tasksel.
Some of the top distros like Ubuntu and LinuxMint have switched to alternate DEs like Unity and Cinnamon/MATE, as their default desktop environment.
Does this move reflect less trust in Gnome 3?
http://www.muktware.com/4087/debian-whe ... nvironment