Given the fact that our gov is promising more welfare through things like the NHI with shrinking tax receipts due to economy slowdowns Im not suprised. We have a heavily burdened existing tax base that cant really be squeezed more and yet they plan expenditure increases. It has to be financed through debt issuance or printing and look how well thats working out for the US and europe!
Unofficial reason: create newsflow to sell into the media and to clients. Bolster Moody's revenues. Moody's needs to differentiate their newsflow from other newsflow (i.e. they're all sick of talking and reading about Europe), so they looked around, cast their bones, had a smoke and concluded that they had been quiet on Africa lately and South Africa was going to be "it" for today.