There's a difference between mass market products and high end audio components. What you are talking about here, applies mostly to lower end gear.
Then, I'd say, you've only proven my point; progress is made mostly with mass (market) products in the context of their production methods and the demand for more size-convenient and power-efficient products. I'd go further though and incorporate the high-end market into the need for convenience and profit maximization which, I'd wager, "borrows" a lot from the cheaper section of audio components, one way or the other. This is less (if at all) about raising the sonic bar in absolute terms and more about working around constraints whose impact is, again, sought lessened.
Then how would you have them write the reviews? Its not like they can see the future and hold off on giving a component a rave review because future models will sound better.
Simply put, I don't need for them to have crystal balls but to put their sonic impressions into perspective. I've heard dealers say, quite often, how a new or more expensive product would "blow away" another (cheaper) ditto, only to feel myself they've exaggerated wildly. It's not only about exaggerating though, but perhaps mostly about feeling they're being mislead by factors that would influence what is sonically perceived. Essentially the same goes with many reviewers.