I really don't understand the reluctance to try different things rather than stick to an obviously failed system.

1. So many people have left that many of the people remaining are on the extreme end of the distribution of liking it the way it is, for whatever reasons.
2. There are no doubt people who (at least in their own minds, and potentially in reality as well) stand to lose from this, and some of them are no doubt attempting to influence the discussion both directly and via sock puppets and all of the usual manipulation techniques that by now well known. Those with less of a direct stake, less of an understanding, or who are generally more impressionable are likely influenced.
3. Plain old status quo bias, fear of change, etc.