Believe it or not, until halfway through the 80s most records were released to the press and radio at the same time as they went into the shops. Radio One wouldn't play a record until it was in the shops.
Since then the pre-release window has been steadily stretched until it's got to the point that the public think a record is out far sooner than it is. This results in a chart in which everything goes directly to number one and then drops straight out again and very few records are actively promoted once they've come out.
The music business favours long pre-release windows is that it encourages them in the illusion that they control the market.
The media like it because they like to feel that they've got access to something ahead of the public.

As DH says, this used to be standard practice. The first place you heard a new record was on 'Roundtable' on Radio 1, and it was in the shops next monday. Going back to the Black Crowes / Do you need to hear a record to review thread; more of this kind of "it's out next week, go and buy it" should be encouraged; journos and punters all on the same page. The chances of this becoming the norm again - zero I reckon.

we are thinking of "doing a Black Crowes" on it. "Well-regarded US supergroup delivers disappointing sophomore effort... 2/5 stars."

Gnarls Barkley have rush released their album a month ahead of schedule.

Music released with minimal hype and reviews written with the knowledge that people might have already heard the record. What's not to like?

Was it MM or NME that had a guest reviewer guessing their way thru' the new singles each week. That I did like, especially if they got it all wrong. A bit like when Cliff Richard was tricked into dissing his own w(h)ine.
Idea revived by the Word in 2008??