Nate Silver had predicted that Obama would get 313 EVs. Obama did actually better and got 332. Not sure if he used the word landslide, but he did say this election is not that close and Obama clearly wins, which if anyone had paid any attention to the most of polls out there, the result was already clear. But then some want to defy math, or don't trust polls, which maybe is the most legitimate reason by far.

And the media just loves sensational BS, so that could be another reason why there are people who are amazed at this result.

Some think that with this record Obama didn't have a great shot at winning, but then you could always compare the end of Bush era with end of Obama's first term and see that everything is better than 4 years ago and headed in the right direction. Then again, right direction depends on the point of view.