There are many and complicated reasons that the press is cowed by the right and responds horribly to criticisms by the left, and I certainly don't mean this is the most important part of it, but one is that they actually know the right is full of shit about the criticisms and that the left is serious. As in, the right is playing a game and the left means it. They (some) like being part of the game. Many in the political press simply see that as part of the role. When the game is give me scoops or the asshole you hate will, or give me scoops and you can get out in front of someone else reporting it more negatively, or let me run this very flattering profile of you on the off chances I get scoops later (a beat so sweet is must be sweetened by the beat sweetener), you are playing a game. Maybe it's a justifiable game, but it certainly will have an impact on how you to approach your job. If they thought the left was just playing a game, too, they'd respond better.
This is actually much worse than it probably sounds.