If that’s your mentality, all technology is technically “Is a waste”. Because a Product is superseded by something else the following year by something better. Why not buy what you enjoy and what somebody wants, regardless if its aluminum or stainless. Itd the perception of what the consumer wants from the product, in the case of the Sapphire display, that alone pays for it self in durability.
Again, some want more a premium product. That’s why Apple offered the stainless model, it’s the next step up with the stainless 316 L. Remember, the Apple Watch is also marketed as a fashion device, and I think the stainless model executes that nicely with leather bands, stainless steel link bands, etc.
I don’t see it as “Throwing away money”, if it brings somebody enjoyment and they want something more premium, That goes for anything in this life that you want something that cost more, you pay a premium for it, Even if it is technology that becomes obsolete. That said, as somebody who did owb the aluminum model at one point, I would never purchase the Sport model again, I thought it felt cheap and I was happy to upgrade to the stainless model with Sapphire display. To each their own.