Well, a lot of it has to do with the neutral media taking cues from the partisans.
On most issues, if the two sides disagree then the mainstream news outlets will try to play it down the middle ("Republicans and Democrats disagree on which candidate did better"), because they don't want to be seen as taking sides, especially on anything that's even a bit subjective.
But after the first debate both sides were saying that Romney killed Obama. It wasn't just the conservatives, but the freaked-out liberals. This time Romney didn't do so well but his supporters are still acting like he kicked ass. So the default position for the news folks is to say reactions are mixed, blah blah blah.