The common explanation you hear everywhere, even here on HN, is that citizens "staying informed" is the key to an effective democracy. While it may be true in the abstract, using this as an argument for 24h news - or even daily news - is quietly omitting the fact that these news sources provide negative information value. Your worldview becomes less accurate, not more. Widespread addiction to breaking news is thus creating a less effective democracy.
Following news makes little sense for keeping a person informed. There are too many completely conflicting sources of news. All the news informs of is what other people who watch the news will have opinions on.
Because the alternative (other than going out for a walk) is watching re-runs of many years old shows or other outright crap.
Personally, I like the 24/7 radio news channel of the local public broadcaster ("B5 Aktuell") - news and information program, but no pop music that was bad already when it came out.
Today I don't get live TV but I do pretty much get real-time news through Twitter, etc.
I studied journalism in undergrad, and I have never understood why people are so drawn to watch these national 24hr 'news' channels. During a major crisis, sure, but day in and day out? I just don't get it. There just isn't that much that happens at a non-personal level (personal meaning self-, family-, friend-, work-oriented) each day. In terms of staying "up to date," I still am not clear on why this is important to do daily at a national-focused level, but if it's important to you, it can be done in a few minutes by reading a brief recap. If you do want a more traditional news cast, PBS News Hour is a good one.
But with these 24 hr networks, given how little of import happens on an average day, most of the time what you are being shown are not facts, but opinions. And these networks are all owned by massive, massive megacorps. Not sure why anyone is interested in getting drip fed opinions that originate, however loosely, from these conglomerates.
They try to get you to buy into them by convincing you it's important to "stay informed," but never really explain why. They play on your desires to be a good citizen, to be seen as intelligent, to feel 'serious.' If staying informed is important, it's most important at a local level, where your real connections can help you have a real impact. People are so focused on what all the senators tweeted yesterday that they are missing the real problems, issues, etc. that they could help address in their local communities. In this sense, news might not come from media at all -- and here is where social media could actually have real value.