You do realize that the corporate interests of the media are called ratings? And ratings usually means what people want to see. Therefore the corporate media interests intersect with what the public wants.
The problem isn't what you are alluding to, which is that corporations or in this case corporate media is some sort of iniquitous cloaked entity that is out there to mind !@#$ the public. Is it the public's fault that has driven the media to cover things the way they do or is it a case of the media conditioning the public to view what they want to show?
Considering that at the end of the day, each consumer has the decision to watch a wide variety of programming, at worst it's a little of both. Most journalists are liberals, so most news that is covered comes more from a liberal perspective. FOX was one of the few tv options for conservatives to get their news, and they were able to monopolize that market, whereas the other channels competed with one another.
The problem is that you have opportunistic members of both the conservative and liberal media who see that there is a market for a certain form of "news", and then they look to push those views to the extreme which conditions viewers to adopt those views.
It's a vicious virtuous circle, think of a feedback loop. Just keeps going round and round reinforcing those views. It's horrible.