I've often felt for us at least that any "belongs_to" relationship should get pulled out of mass assignment by default. 95% of the time I imagine in the world, a belongs_to field on a child record is not going to want to be updated by some mass assignment, but is assigned instead by instantiation parent.children.new or manual assignment. Child.new(:parent=>parent)

Would this be a valid change to Rails. All belongs_to attributes are by default not accessible to mass assignment?