Walter,

If a product is supposed to do something, and is supposed to last a certain length of time, and does it, then it's a quality product. If another product doing the same thing, says it's supposed last the same amount of time, but actually lasts longer than that, to me, it isn't a higher quality product. Why? Because when I go to buy the product I'll look at the two and make my decision based on the price. This is especially true if I only foresee using the product for a period less than the expected life of the product.

Requirements can generally be reduced to what something is supposed to do and how long is it supposed to last. Certainly, there are exceptions.