Most of these ‘idea’ threads start out negative anyway. The person who initiate these threads, usually have some selfish agenda spurred from a recent personal loss incident. All attempts at explaining the current mechanics and how the suggested change make no sense, are just deflected with hostility.
Recent example thread
So if we’re to moderate ‘negative’ responses towards other people on the forums, we should be equally zealous about moderating these useless ranting threads.
On another game forum, the way they’ve solved this, is to have a specific ‘ranting’ section where they allow a lesser moderated exchange between people, while the rest of the forums are more strictly moderated.