Since Fox News has been in America, they have always catered to a market that was being overlooked. That is why we still have innovative television series such as “Married With Children,” “The Simpsons,” and “COPS.” These three shows alone paved the way for “Two and Half Men,” “Family Guy,” and pretty much any reality TV cop show on-air today. 
These shows were designed to hit “Middle America,” who could not identify with upper middle class standards of NBC, ABC, and CBS networks of the world. The people in “Middle America” also tend to share the same views about religion and politics.
Rupert Murdoch, the owner and current CEO of Fox News, was brilliant at creating news as entertainment; hence “A Current Affair” and now “TMZ.” Most other major networks tend to lean left, so that leaves a huge void for Fox News to fill. With Fox being the only news network exploring that relatively uncharted avenue, their ratings are extremely high. Everything they do is polarized, while the other stations fight and bicker for the left leaning viewers. Fox News has no competition for their demographic. 
From a marketing standpoint, “Middle America” was, and is, a good market to go after. It had not previously been addressed directly, and until the advent of Fox News, it wasn’t seen as appropriate to be blatantly biased. Making news into “entertainment” is inexpensive, simple, and highly profitable. Making your entertainment polarizing and divisive generates buzz in and of itself, intensifies loyalty of inclined viewers, and again, is that much more profitable.  
Many claim Fox News is a response to “liberal bias” in mainstream media. The problem is that journalism has traditionally been understood to be “biased” in favor of the public and human good. As the political climate’s grown more and more polarized, this has been misread as “liberal.” The truth is that public and human good tend to be furthest from the agenda of the political right and closer to the left. It’s become a case of guilt by association for the mainstream media. There’s no such thing as “unbiased” news or media outlets. There must be a “bias” because information has context and implications.
Thus, the real issue is not the presence of bias, but the compass which guides the bias. Who or what is a given bias seeking to serve, benefit, protect, or profit? Who or what is it seeking to alienate, harm, or neglect? What are the short, mid, and long-term implications of said bias?
Fox News will always act as the counterweight to the left of center bias, which dominated the airways prior to their creation. “Fair and balanced” refers to their assertion that their bias is fair, given that similar bias is the modus operandi of all the other networks. Begrudgingly, they have a point. If you really watch all the networks objectively, their bias is plain to see, and no less than Fox. The bias in Fox is perhaps easier to spot, simply because they are the odd network out.
Frankly, I think all of the networks should be ashamed of themselves. Ethical journalism has gone out the window. We have replaced factual reporting with absurd analysis from stacked debate teams made up of lobbyists and have political extremists as anchors. Every story is followed by a judgmental quip from the Wolf Blitzer or Megan Kelly figurehead.
NBC, MSNBC, FOX, CNN, HLN, ABC, CBS, and their fellows in print have largely abandoned all ethics and principals in pursuit of the power to shape narratives for political purpose. FOX is more open about their bias and happens to be biased in a different direction than the others, but they are all birds of a feather. And I have contempt for anyone who gives “their” biased sources a pass simply because it is in their favor. Long term, we all suffer from anything short of objective and factual reporting.
One also has to realize that people like Murdoch have very large influence over what the world perceives as fact.  He is competing with other billionaires who have agendas of “fact” that they aim to push as well, and its all in the name of advertising. Larry Page and Sergey Brin of Google, Warren Buffet of General Electric and the Washington Post, and Carlos Slim of the New York Times all possess global agendas. 
Murdoch, as any billionaire trying to make it in this world, is playing his position, and if one is able to recognize that, then the transparency in his reason to support the Republican Party is all the more clear.