And in the case of celebrity interviews or book extracts, there is money at stake too - for the client and their representative.
Even Greg Dyke's memoirs - sold by rights managers at his publishers rather than his book publicists - were billed as 'exclusive' in The Mail on Sunday and The Observer as much of it was repackaged as news stories at least once.
Giving exclusives also has the benefit of pandering to the vanity of newspapers as much as their circulations. It does an editor's ego no end of good to be told 'I'm giving this to you first', as well as securing good coverage.
There is giving exclusives and then there is giving exclusivity. If you find yourself promoting someone or something that is fairly 'b' list in terms of whetting a journalist's appetite, you generally find they will only take it if it is offered to them as the one and only. But some people have exclusivity immunity. Philip Green of Arcadia does, and so does (bizarrely) Sadie Frost. And how many profiles of Boris Johnson have there been this summer? Oodles; because people waive exclusivity just to get him in their papers.
Try offloading your worthy story about a local council's achievements, or a good campaign of some kind or another, and see how far that gets up the newslist in a morning conference these days.
Under these circumstances, exclusives and exclusivity have come to replace the photo stunt for getting media coverage.
Reports or surveys are winners, and used by think-tanks to great effect.
The exclusive's best friend is the embargo. My favourite embargo-for-its-own-sake story? PR icon Lynne Franks recounts in her autobiography Absolutely Now! that the massive success of the mail order Next catalogue was down to the fact that it was under embargo as a launch strategy.
Unless you have a simultaneous launch in different time zones, my advice is don't go for embargoes: If you don't break them yourself in the rush to provide an exclusive, the media will anyway.
I'll say this about exclusives, though: nice work if you can give them - or get them.
Julia Hobsbawm is professor of public relations at the London College of Communication. Kate Nicholas is on maternity leave.