GNOME 3 has fallback mode with gnome-panel and metacity. In 3.2, various applets have been made to work.
Seems somewhat weird to say that the newer versions of gnome-panel, metacity and gnome-applets, which all received new versions, should somehow not conflict with previous versions. They've always conflicted!
Work was done to ensure these modules work with gtk+3.0. Bugfixes have been applied, etc.
If you want one version of a module not to conflict with another, either do the work, or have someone do it. But don't complain that anyone "dropped the ball".
I'm running gtk+2.0 applications perfectly fine in GNOME 3. I dislike gtk+1.0 themed applications, but they'll work as well.