The luxury purchase folks are certainly getting a better deal as apples:apples prices go down; but if you're paycheck to paycheck and used to be able to not buy a smartphone but now have to - you're just running on tighter margins.
I would imagine measuring economic well being directly through something like a "economic desperation index" makes more sense than doing a bunch of calculus on comparing the price and quality of items in two different years since the latter would only apply to people who own the item in both domains. Especially in the context of this article which is discussing if people have it better now or then.