A fair position, but value is part of the decision making process of anything we buy. It is proper to downrate an unreasonably priced, but serviceable, product. Similarly, it is appropriate to upgrade an item that performs above its price point. The reviewer should however make clear that this is the case in each situation.
If anything is up for constant debate, it's how much a book should cost, with many people unwilling to compromise past a fixed point. (See: this thread.) As someone who is more flexible, I don't want someone using that in their ratings and forcing me to have to guess what the book would be had they not done that. On the other hand, people who do have that line, don't want a more flexible person assessing that way either. While you say the reviewer "should" make these things clear, not all will (or do) and the disclosure will most likely involve the words "too expensive" or "what you could expect for the money." Oh, and what price is that person talking about? Is it the same now as when he wrote it?
All other things being equal, the guy who bought the book when it first came out, the guy who bought it when the price got lowered by a few dollars, and the guy who got his copy when it became a freebie for a week, all assessing by the price they paid -- which can change again -- confuses the issue needlessly by entering into an area that is not their business -- what someone else should pay.
By this system, indies would get a great head start for being in the .99 to 2.99 range. It's hard to argue that .99 isn't a great price and it allows in one of my favorite "songs" -- You only paid a dollar, you're an idjit for expecting a professional effort.
It's hard to say something isn't worth .99, so I prefer to stick to if it felt worth my time.
Established author with decades of experience would start out in the hole for 14.99, because a lot of people think that's too high no matter what. People, for the most part, just want to know if you think their favorite author is slipping. If you don't think he is, the potential buyer thinks you have similar sensibilities, and you talk about the actual book, the reader can figure out the pricing on her own. This is true whether the potential reader has a firm stance on pricing or not.
Oh, and how many reviewers are keeping up with the prices and fixing the ratings accordingly? If 1% do, it'll be a miracle. How about when it does it again? That's not even bringing in blogs. The price can change, but what's "inside" -- for the most part -- doesn't.
Like I said, I'll mention price in a review -- and possibly how my life would have been happier had I received the fancy doll house for Christmas when I was a kid (or now) -- but it doesn't figure into my final assessment.