Well, first of all the idea that news media should be neutral and objective is a fairly recent, and mostly America-only, notion. The history of newspapers, for example, is full of publications which were openly and viciously partisan to a degree that offends modern American sensibilities. And even within my lifetime that's been true to a certain degree: as I was growing up, the largest nearby city supported two daily newspapers, and everyone knew and openly admitted that you either subscribed to the Republican newspaper or the Democratic newspaper, and did so based solely on your own partisan affiliation.

So if the news media is currently significantly more partisan than it had been in the previous few years, it's unclear whether that would be something new and unprecedented, or just a regression to historical mean.

Second, I don't necessarily think we're seeing a rise in overt organized partisanship by major/"mainstream" outlets, so much as a combination of several factors:

1. Many journalists now feel that they were an unwilling part of Trump's campaign, in the sense that they were played in order to give Trump free media coverage that other candidates never got, which in turn gave Trump broad nationwide exposure at a time when his campaign was struggling to get off the ground. This is not something that feels good to them, and since they were so late on recognizing the playbook (regardless of anyone's personal opinion on the ethics of that playbook) they now are -- not surprisingly -- looking for a way to cover Trump that doesn't just repeat the debacle of the campaign.

2. But an interesting corollary to this is that Trump is almost the perfect person for them to cover in the modes they'd been used to. The way he operates produces a never-ending stream of outrage, scandals and "breaking news" to breathlessly report on, and he seems to thrive on it, creating a self-reinforcing cycle. His campaign recognized very early on that outrage works as a strategy, but the problem with being a continual source of outrage is that it makes you look outrageous.

3. Trump seems to be having a lot of trouble making the transition from candidate to officeholder. Historically this is something that does cause trouble for populist "outsider" candidates when they get elected: as long as they're on the campaign trail they can drum up support for themselves and against the system they say they'll fix. But what happens when they're no longer the outsiders, when they are the system? That's where Trump is right now: he's still largely running the campaign playbook, but the campaign has been over for months. And the result is he's in trouble. When the coverage was Trump versus someone else, when it was about him unloading on opposing candidates, he could make it work in his favor, because that's just how elections work. But now that he's sole winner and serving President, it looks a lot worse: people like a bully in the campaign but not so much in the Oval Office.

4. It is absolutely true that trust in media, and in experts and intellectuals of all types, has declined precipitously in recent years, but it's also true that promoting this decline has been actively cultivated as a strategy by certain political entities, many of them on the conservative/reactionary part of the ideological spectrum. It's unsurprising, and in fact completely expected, that one of the consequences would be increased media scrutiny of those entities, even if only out of self-defense.