Yeah the days of DE's offering fallback modes seem to be coming to an end. If you are interested in using a DE that doesn't require 3d acceleration, I would wholeheartedly recommend XFCE. XFCE and Cinnamon are my favorite DEs for Linux. If you despise Gnome3's accelerated mode I would urge you to give Cinnamon a shot. It's clean and awesome, though not as customizable as XFCE.