Most Republicans seem to constantly fall for the the "I didn't do anything wrong, the liberal media is just out to get me" non-sense, so it shouldn't be any surprise that most Democrats seem to fall for the equally absurd "I didn't do anything wrong, the conservative media is just out to get me" version. When politicians in either party face criticism, negative news stories, or become embroiled in scandals, one of the easiest and most reliable responses is to claim or imply that it is just part of a smear campaign by the right/left-wing media.
In reality, the media doesn't have an ideology, for example I doubt most of the commentary by the talking heads at Fox (or MSNBC for that matter) is informed by any sort of genuine ideological conviction. Certainly nothing beyond the generic "I'd prefer for this party to win, I guess" that most voters probably have. There are occasionally instances where the media is clearly in the tank for a certain candidate (Cory Gardner in 2014, Obama during the pre-New Hampshire part of the 2008 primaries), but such instances are few and far between. The media isn't treating this non-story about the e-mails like a big deal because they're part of a right-wing conspiracy to bring down Hillary Clinton. They're doing it because it is in their interest to do everything they can to create the perception that the Democratic nomination race isn't a forgone conclusion (so more people will watch their coverage of it) and because it is clear by now that their is a significant audience for stories about the Clintons that reinforce certain perceptions most Americans have of them.
At the end of the day, the media only cares about making money. If saying stupid sh!t for attention, race-baiting, affirming the worldview of a particular party's base or certain demographic groups, sensationalized "reporting", fear-mongering, misinforming viewers, treating non-stories as Big News, etc boosts ratings and thus leads to more advertising dollars, that's what they'll do. If such things didn't work or stopped working, they'd try something else.
Even the media's corporatism likely stems more from the financial incentive to promote the economic interests of the companies that own ABC, NBC, MSNBC, FOX, CNN, CNBC, CBS, etc than from any sort of genuine ideological commitment to a pro-big business ideological agenda. This probably contributes to the lack of investigative reporting a little bit, but that can probably be primarily attributed to a combination of laziness and most importantly the unfortunate fact that investigative reporting usually doesn't produce stories that attract as many viewers as CNN babbling about a missing Malaysian airplane (whose direct impact on the viewer or someone they know well can be fully explained in no more than two concise and simple sentences). Actually, that's probably a good test for how damaging a scandal will be (how many concise sentences would it take to convey it's significance and impact to someone who doesn't follow politics at all).
Side note: This is also why affairs are such dangerous scandals compared to something like campaign finance violations. They are easy to sensationalize and they can be easily described: "Senator ___ cheated on his wife. If he broke his marriage vows, how can we believe anything else he says?" With campaign finance violations you have to explain why these laws even matter, how the amount of money someone gave to Senator ___ exceeded the legal limit and that they tried to get around the law by...zzzzzzzzzzz.
At the end of the day, the media only cares about making money. If saying stupid sh!t for attention, race-baiting, affirming the worldview of a particular party's base or certain demographic groups, sensationalized "reporting", fear-mongering, misinforming viewers, treating non-stories as Big News, etc boosts ratings and thus leads to more advertising dollars, that's what they'll do. If such things didn't work or stopped working, they'd try something else. But again, even the "news" networks whose business model involves blatantly supporting one party over the other, they don't necessarily do do so in a way that benefits the said party.
Take Fox News, they don't always act in a way that benefits the Republicans politically and have hurt the party quite a bit. Often when the Republican Party is trying to avoid jumping off a cliff, Fox works to rile up its viewers to the point that it turns a fringe position into the mainstream one within the party (even as folks like Boehner know better). As a result, what could've been a Ted Cruz or a Steve King embarrassing himself again turns into the whole party stampeding off the cliff like swarm of lemmings. What Fox does do very well, however, is stoke the resentments, play to the fears, exploit and encourage the prejudices, and yes, even speak to the concerns* of certain demographics (especially white men who are either 60+, evangelicals, or members of the working class) that feel like no one is fighting for them and/or that the country has changed so much they barely recognize it anymore...and that they were left behind when it did so. Frank Luntz once observed that "We don't watch news to inform us anymore, we watch news to affirm us."
*This is a distinctly different thing than advocating for a group's actual interests, which Fox has never done.
That's exactly what Fox News does, it makes money by affirming the worldview of certain groups and giving them a sense of validation about their fears and prejudices. It happens that in Fox's case their audience means part of their brand will be promoting a right-wing worldview, but I'd bet a lot the more extreme, hysterical, and/or bigoted comments and personas of people like Bill O'Reilly, Glenn Beck, Mike Huckabee, etc are just schtick. A lot of that stuff is likely just an act, these guys are entertainers in a perverse sort of way. It’s like Beck, Huckabee, etc are screenwriters and their TV personas are the characters they’ve written for themselves.
Everyone has there own little niche at Fox (and MSNBC, for that matter). O'Reilly is the chief race-baitor, Beck used to be Fox's "the government is out to get you" guy, Huckabee is the lead cultural warrior, Hannity does the most blatant pandering to generational animosities of older viewers, etc (although the niches all inevitably overlap at times).
MSNBC does that same thing, but for different demographic groups such as college-educated white liberals in suburbia. They’re just as shameless as Fox though and just as insincere in their commitment to their so-called ideology. Also like Fox, they don't truly help the party they are associated with. Watching the likes of Chris Matthews or Ed Schultz is like having every negative stereotype about liberals reinforced. MSNBC's talking heads generally have a smug elitist persona and preach tolerance while promoting bigotry against minorities that don't vote how they want them to ((*cough* Lawrence O'Donnell *cough*).
They also play to their audience's class and cultural prejudices against religious and rural Americans by constantly looking down their noses at the rural poor and paternalistically acting like white southerners and the white working class are all a bunch of dumb, racist hicks who need a good educated liberal to come and tell them about what their interests are. The liberal version of the "here in the Real America" schtick is constantly bellowed by MSNBC: "If only the dumb rednecks would listen when we tell them what's best for them, everything would be perfect in America."
And what does this sort of non-sense do? Well, for MSNBC's target audience, it affirms their worldview and gives them a false feeling of validation about their prejudices. But it also ensures that anyone who watches MSNBC and isn't part of its target audience will likely come away with the impression that liberals are everything the Republicans accuse them of being: smug, arrogant, and hypocritical elitists who think they know whats best for everyone else. MSNBC doesn't care if this hurts the Democratic brand with independents or reduces the chances of rural Americans voting Democratic again. They only care that there is money to be made promoting their warped and distorted pseudo-reality.
TL;DR: The media isn’t babbling about the e-mails because they are part of some vast right-wing conspiracy to bring down Hillary Clinton. They’re doing it because, for whatever reason, there is an appetite for anything remotely dramatic (or pseudo-dramatic, in this case) involving the Clintons. Thus, it is in the media’s interest to peddle this sort of non-story and treat it as if it were a big deal. The idea that the media has a commitment to anything for reasons other than its own direct financial self-interest is laughable.
