Most publishers do assume some relation between review and sales. It is not direct, and it's hard to tell how much influence they have, but are you really denying it exists at all?
Now it might be true that at this point the relevance has gone down. I usually publish reviews quite a while after publishing since GB's reviewers spend a lot of time one games. Does it make me irrelevant? Maybe.
I'll be curious to see Dragon Age 2's sales numbers.
Reviewing is in a ditch. In Wrestling, people buy their seats to cheer and boo wrestlers. Controversial is the best as it appeals to both sides, those who like and those who dislike. Makes more money.
Video sites/magazines etc… are tools in the marketing strategy.
Pre-term/short term as a promotional outlet for publishers to build up the hype, peer pressures, group effects… (releases of features, teasers, exclusive interviews and all) and in mid-term/long term as validation of the sales realized during the short term life of a game (this is when marketing starts to advertize for the game through the reviews notation and selected extracts)
Reviewers are entangled in a circular environment. Hype impact often supercedes reviews impact. This, in addition to buyers' behaviours, leads reviewers to adapt their notation to the predicted sales on short term. A game expected to sell well is generally noted high. Even better, the mark does not correspond with the content of the review.
Here's the described cycle:
-publishers build up hype successfully=>pre-ordering/purchase on release/first week of day of the game is big=>to match the perception of the first batch of buyers, reviewers set a high mark on the game=>publishers use the review marks (selectively) to advertize for the game in mid term/long term. Self validating environment.