To play Devils Advocate for a moment: Why do we need, or even want, a newspaper to endorse a President? How does it not undermine a paper's journalistic ethics to be neutral and fair?
I can read a biased story, with values very different to my own, and still draw conclusions that are still meaningful. Mind you, I would expect omissions and couching that is flawed, but understanding the thinking of those I oppose is valuable and allows me to see their blind spots (or my own for that matter).
But a news organization or journalist being clear about their values and politics also disposes of the harmful notion that they've actually achieved some sort of objective reading or that they're being complete and well rounded. There's a deceptiveness in that pretense which some readers (watchers) may actually take for truth and not think more critically about what they're consuming than that.