I think the beauty is important too, because it can show to new people that a
truly free system can be wonderful in a glance.
Although is important to worry about desktop environments that require too
much memory: many people outside Europe and North America still have
computers from five to ten years ago. that's why there is a LXDE version.
I know that this topic come and goes once in while, but my vote would be to
using MATE or XFCE as the default, and leaving LXDE behind.
Both MATE and XFCE are lightweight enough without the ugliness and
inconsistence of LXDE. Both of them are based in GTK+2, so they have all the
legacy of hundreds (maybe thousands) of beautiful themes easy to change. And
they are consistent because they don't rely much on applications from other
desktop environments.
Beyond that, the new Xubuntu 14.04 is outstandingly beautiful with his
elemenary-os feeling. http://xubuntu.org/screenshots/
Even if is not choose, it would be nice to have an official way to implement
the Xubuntu configurations at netinstall.
