Using a better compression algorythm (LZMA2) is also planned by Debian maintainers to make gnome fit on the CD.
So this commit will probably be reverted before the final release.
It might be that the 700MB size limit is just an excuse to dump GNOME 3 and not the most important reason. Given the conservativeness of Debian releases, I wouldn't be surprised if the Debian team decided to wait for GNOME 3 to become more mature. Remember, Debian shipped a stable release with KDE 3 even after KDE 4 was released.
