Because the debate was settled in 2012.

If a literal pile of dead first graders doesn't overcome money and influence in the national political will, nothing can. It's a pointless discussion, whether it's street violence in Chicago or domestic terrorism from white supremacists. We know what the answers are and the solutions are pretty straightforward -- the rest of the industrialized world seems to have come around to it -- but in lieu of political will to do it we have thoughts and prayers to keep us warm at night.

The only mildly new angle here, and it ain't that new, is the rise in white supremacists taking out their rage on minority communities. Charlie Pierce said it best yesterday in a column, the days of lynch mobs are over, because the lone shooter is his own lynch mob. Easier to fire into a crowd you don't like than throw a rope over a tree.