This is actually one of the best authors people can read from. Regarding your second link, Krugman has already admitted his prediction did not come to pass.

On a number of issues Krugman has proven a good deal more accurate than other economists, such as: -Whether or not Federal Reserve would cause inflation -Whether the stimulus in 2008 would help the economy -Whether or not Obamacare would work and more on his near daily blogging/tweeting.

Sure he's definitely made mistakes, but who hasn't, and at least he has owned up to them.