Follow up to my own post of new thoughts... The idea of follow-on effects from improvements in project atmosphere is one that can be extended. We could, for instance, view the controversial content issue as a symptom of a community imbalance that could be improved indirectly and with less resistance than the "direct approach" image filter.
I have no basis for this other than a gut feeling, but it seems like subject matter (page content like images etc.) is less a barrier to entry than the contributing environment. Perhaps first focusing on environmental improvements would alter the community in such a way that controversial content issues could be resolved organically.
Nathan