Debian just released their beta 2 version of Debian Jessie Installer. And they claimed that the Gnome is the default desktop environment again. They were doing the right thing in both last year's XFCE default and now the GNOME default actually.
There is nothing right or wrong in the two decisions, because both of them are reasonable and very objective.
Debian is very serious in their policy of using free software only, although they are still not endorsed by the Free Software Foundation, because of hosting non-free software repos in their official servers and websites. A fully free operating system has a lot of problems currently, especially in graphic driver perspective. Gnome is a good desktop environment and it completely uses OPENGL to render their desktop -- Gnome-shell. However, if you are using free driver or free firmware without 3D support, gnome-shell will be fallback to a "Classic" version. This "classic" version is nothing bad at the first glance. Nonetheless, it does not have any accessibility support. It means that people with disabilities would feel difficult to use the "classic" version of gnome-shell. For better accessibility support, Debian changed their default desktop environment to XFCE in last year.
XFCE looks old and very traditional. Compare to Gnome-shell, it is not very beautiful or eye candy. However, Debian still used it by default because of social responsibility. Free software and computer technologies cannot refuse people with disabilities. Every decision should highly consider their convenience. This is what Debian did.
Now they change back to Gnome-shell. Our computer hardware fully supports free driver, so we cannot verify if Gnome-shell will be fallback to "classic" or their classic is better for people with disabilities right now. However, we do believe that Gnome-shell is working with Debian development team very well, and they may improve their accessibility and fix bugs at this point. Even though it is still buggy, but we believe that in the future, they will eventually fixed it. This is what free software means.
In conclusion, both decision is reasonable. Furthermore, in the new Debian Jessie Installer, there is an option that people can choose another desktop environment or even choose more than one desktop environments. Therefore, it is not necessary to raise a "war of desktop environment".
Have fun, be free.