There's a joke Quakers tell: "I'm not a member of an organized religion; I'm a Quaker!" The same sort of thing applies to being a Democrat. If Democrats aren't arguing, they aren't Democrats. Being a Democrat is a lot like being in a family -- what binds you together is barely enough to overcome the things dividing you.
In other words, Democratic strife is a 'dog bites man' story. What bothers me is the way that the news network seek to impose a narrative on events. I guess this is how they attract viewers, but it's not serious journalism. It tells us nothing about the character or policy positions of the candidates. It punches up the drama of the horse race.
What would happen if they just gave it a rest? If they reported what the candidates said, and let people draw their own conclusions? I think that most people would just discount the bickering as being 'politics' and then move on to the rest of the news.