We needed to update the software to keep up with the security updates to our community and to support newer versions of the platform that runs the forums. Old stuff doesn't support newer security updates (they need to stop updating it at some point to focus on the new stuff), so it leaves us potentially with software or platforms with security holes in them. It's the same reason most people don't run Windows XP any longer...

Unfortunately, software updates bring along changes to features already in use, or additional features. We can't fix the fact that the authors of the software decided to redo how the social groups work, unfortunately. Sorry.