I don't think the blue back covers are inferior, just a different color. Evidently the way the blue pattern floats in the plastic molding is hard to repeat uniformly across all manufacturing processes (or even the same process). It's more like tie dye. It's almost impossible to get two tie dye products to be identical. If Samsung wanted all blue phones to look identical, then they made a poor choice. I think the value lies in uniqueness of blue, gray, purple variations. Sameness tends to be a bit boring.