The industry rule on labeling has an important purpose and is taken seriously. Without this W grade labeling rule, companies can formulate a 0W-40 oil and market the same product as a 0W-40, 5W-40, 10W-40, 15w40, 20W-40, and 25W-40. It would certainly save the oil company manufacturing and inventory costs, but would deceive the customers.
Engine oil viscosity is very important and consumers are entitled to receive the grade they want to purchase. It's not up to us to tell them what we think is best for them.
Tom NJ