What's wrong with good words like 'decline' and 'percent?'

A NYT article today read "Australians can avoid even a single quarter of negative growth during the current financial meltdown if they do not talk down the economy, the treasury chief said Wednesday."
What is negative growth? Why not just use the word 'decline?'

The term "basis points" is used commonly, as in "the interest rate is up 200 basis points." Why not say that the rate is up 2 %?