There should be rigorous debate. If you look back in trac at some of the least popular changes, those were the changes that typically had the least discussion or where dissenting opinions where just outright ignored.
Disagree on each version of the community mod being disliked. To be honest, all the versions before 26.6 were pretty widely liked at initial release and those changes are still widely approved of.
There are mechanisms to reverse changes. Indeed, we appear to be in the midst of changes with buildingAI and melee rebalance.