Why is the mainstream media failing so spectacularly, right before our eyes? Well, the easy answer is that "they've stopped being objective." The problem there is that lefties say that too.
The truth is that there's more to it than that, and the issues are many and interconnected, and they beg the usual chicken/egg questions. Let's look at the major ones.
One problem is that most journalists, other than the glitterati top tier, are paid terribly, are managed incompetently by harried and unqualified supervisors, and quickly learn that they get paid the same for slipshod, careless and even biased reporting and writing as they do for performing their duties in an exacting, thoughtful way. Indeed they find, over time, that making the effort to be fair and unbiased is penalized, and that they move up within the newspaper clique by parroting the cynical tone that surrounds them.
Most people have noticed that the problem has gotten much worse in recent years, and that, while it existed before, it was not nearly the pandemic it now is. Why? Simply put, young, poorly trained, careless reporters have gotten older, and have become middle-aged careless editors and managers, who have no interest in fairness and honesty in what they produce, a message that has been conveyed loud and clear to subordinates.
Combine that with external factors: As the already-frenetic pace of journalism has continued to accelerate, due to the arrival of 24-hours news networks and then the internet, there's less and less time to tell a young reporter that his copy stinks and is full of personal bias--especially when, the next day, the bias-filled reports get an "atta-boy" email from the managing editor.
And, as news audiences splinter into thousands of segments, the competition for eyeballs becomes so fierce that accuracy takes a back seat to "attitude." When the goal of every journalist is to reach that highly-paid top tier, presenting every story with a unique slant, rather than simply getting the facts right, becomes the priority.
And then there's, quite simply, the erosion of the meaning of concepts like "facts" and "truth." In a world where one man's terrorist is another man's freedom fighter, where concepts like "political correctness" are openly imposed by those with an agenda of moral equivalency, where high-level government officials, in sworn testimony, question the meaning of the word "is," it becomes almost quaint to suggest that reporting a story one way is right, and reporting it another way is wrong.
The worst part is that all these factors, unlike their temporary bias against the President, cannot be easily reversed, rethought or undone.
And it means that this problem is only going to get worse.

Inside the newsrooms themselves, they don't see all this. But they're scared. They're scared because the dirty little secret of professional journalism is becoming known to the public at large--the secret is that journalism is like juggling: with varying success, anybody can do it.
At best, it's a craft, a skill the basics of which nearly anybody can master with a little practice. The more I've been a working journalist, the more strongly I've felt that four-year journalism schools (like the one I came from) are a massive waste of time. As a profession, it's more akin to plumbing or carpentry, something where you can absorb the basics in the classroom, but only time on the job will make you proficient. Prospective journalists should get two-year degrees at most, and then enter something like an apprenticeship, where they would gain the working experience they'd need to do the job right. A journalism degree no more prepares you for a job as a journalist than reading the "The Joy of Sex" prepares you to be a high-class call girl; but conversely, as with prostitution, you are born with all the skills and tools you need to become a professional journalist--you only lack the on-the-job experience, and the willingness to do the work that needs to be done.
This terrible secret, the fact that 90 percent of the inhabitants of most newsrooms are no more (or less) qualified to be there than you or I, is now being exposed, as the blogosphere slowly supplants the MSM, and people make the stunning discovery that they are getting their news faster, and with approximately the same level of basic mistakes, as they had been from the MSM.
I mean, ever read a newspaper article about some issue or person that you are very close to, that you are intimately familiar with? I'm sure you have. And I'm sure you noticed the errors in the article--most of the time just trivial stuff, but still, errors. You may have wondered: "Gee, I only noticed those errors because I'm so familiar with the subject--I wonder if all the other articles in the paper are that error-ridden, and I just don't see them because I'm not as close to the issue?"
The answer is yes, they are. And all those scared newsroom denizens know THAT too. And they are worried that it's another little secret that is slowly leaking out. But instead of fixing it, they're like the employees in a buggy-whip factory who try to convince anybody who'll listen (including themselves) these new-fangled machines are a fad, unreliable, unproven, that the public will never stop needing their services.
Typically you'll hear them gripe about how there "no checks and balances, no fact-checkers, no code of ethics, no professional associations or peer review."
This complaint, which reveals more about the ignorance (and elitism!--one of the unspoken messages of this complaint is "it might not occur to those conservative dimwits to be skeptical of what people say in blogs") of the speaker, has been answered many times. 
The mistake is in conflating one element with the whole. I would never suggest that this blog or any one blog be one's sole source of news. No blogger worth his/her salt would. They would tell you to get out there and read a bunch of blogs, follow links from one to another, see how (or if) information is being gathered first hand, how information is being shaped--then make up your own mind, rather than letting somebody else make your mind up for you.
The blogosphere doesn't need formalized checks and balances, fact-checkers, codes of ethics, professional associations or peer review, because the blogosphere itself is a self-correcting organism with checks and balances and fact-checkers built in. It is peer review personified. It's the marketplace at work: Do a good job, post accurate, interesting stuff, demonstrate ethical behavior and your audience will (eventually) find you. Post inaccurate stuff, be unreliable, get proven wrong again and again, and your audience will ebb away--or if they visit your site, it won't be for information, it will be to gawk (case in point, the 2004 crash-and-burn of Andrew Sullivan).
You know all that, of course. But in many newsrooms they still don't.
The people you'll hear yelling this stuff the loudest are the people at the bottom of the the ladder in newsrooms, the people just out of journalism school. I do feel sorry for these kids. They've borrowed money, spent years in college, they want to go out there and make a difference, be a real star in the buggy whip industry--and now the profession they've prepared to enter is withering away in front of them. 
But the profession should blame at the institutional flaws that caused this failure, not the institutions that sprung up to fill the vacuum those failures created.