As far as I know, the purpose of the role back is to revert to a more stable version to reduce the frequency of crashes. Also, it is a widely shared opinion that the gameplay dynamics back then were more fun and enjoyable prior to the weapon balancing etc. So all in all the role back is a good thing for the community as far as I can see.
Law pretty much hit the nail on the head Vanilla, being the most popular server at the time, was rolled back as an experiment to see if rolling back all the other servers was a viable fix, then west, as the most popular modded server was next in-line and we are now currently monitoring both servers (for now it seems to have helped ) then I believe the plan is over time to add back some features that were lost, making sure whatever is added back isn't what was causing the crashes
