No grade 4 war supplies: bug or poor planning?

As of 4.1, grade 4 mats aren't used in war supplies. Instead grade 6 mats have been doubled up on, used in combination with both grade 5 and grade 7. This creates a greater demand for grade 6 than would otherwise be the case and makes grade 4 fairly useless (as they aren't used for anything else besides leveling).

Has there been any discussion of this on the forums or any commentary on the change by Bioware? It seems a strange (and poor) design choice.