Travs I think that possibly one of the biggest problems is that so many of todays threads go off topic and often the newer posts have little relevance to the thread title.
Wheeze I feel keeping a Forum true to it`s cause is key to it`s long term survival, for my part if I want to debate an alternative subject with like minded folk then I seek them out where you would expect to find them e.g. Religion then a church or religious forum/website is where I would head for.
You are right the grass roots of this forum are too valuable to be put at risk.