Some people are under the impression that "media relations" mean "bribing" the media! Well, this may be standard practise in some countries, where you have to pay to get your story in the papers (and perfectly legal, too), but not here in Malaysia. We're moving that way, though, as more and more media organisations tend to give priority to paying advertisers. Which is not to say that you won't get your story out if you don't advertise - it just makes it easier!
Which is why media relations is important. Editors want to know who they're dealing with, and it helps if they can put a friendly face to the organisation. It also helps that they know who to call when they need a comment on an industry issue, or a news item relating to a specific organisation.
But as important as media relations is, it still doesn't guarantee you'll see your story in print - as always, it boils down to the story you're telling, and how the editors perceive its importance and relevance to his readers.