This would be an authoritarian action, compared to just opting out of supporting something. There's a huge difference and I think these organizations' supposed interest in ethics precludes that sort of move.

DRM is not illegitimate. It just sucks and operates in a way that is immune to free market competition - the reasons for that immunity are the true thing to fix. Users should have alternatives as there is a clear market there. If DRM is so bad, then that's what should kill it.