Debian developer Joey Hess said that the decision to go back to the GNOME camp was based upon the accessibility, systemd integration, and other factors mentioned on the Wiki for the Debian desktop requalification for Jessie.
This is not to say that GNOME is all great and everything is a bunch of fluffy bunnies for Debian and the interface, which has been getting a bit of a bad press lately.
Hess said that Debian could still go back if things do not improve. Some desired data is not yet available, but at this point he was around 80 per cent sure that GNOME is coming out ahead in the process.
“This is particularly based on accessibility and to some extent systemd integration… The only single factor that I think could outweigh the above is media size, if there was a strong desire by Debian to see a single CD with a standalone usable desktop,” he said.
The Debian live team doesn’t care about fitting on a traditional CD and Hess does not care enough about any more to make it a hard blocker on the default desktop.
The GNOME community is still larger and GNOME 3 has improved a lot.
Debian 8.0 Jessie will likely be released next year. GNOME 3.14 stable is coming this week and should be ready for the next major Debian update.