This may be... whatever, but it strikes me: people who use Twitter, read and write, constantly... every day, many, many times a day, and use it every time they have two minutes free, and often if they don't... doesn't this just have a strong whiff of hyper-activity? The sort of thing we give school kids Ritalin for?
I'm not saying it is wrong, and I have a lot of these addictions myself, but I do think that obsessively skating as fast as you can on the surface of things (140 characters is superficial), in constant anxiety of missing what has been going on for the last hour you were away, indicates a mental state of inability to sit still, and to consider the deeper and less Right-Now-related issues of life.
And intuitively I feel that the very most important issues in Life, The Universe, and Everything are things which do not happen and disappear within an hour or a day, but which have relevance over hundreds, even thousands of years.
For example: what the current president has done today is less important than what he does over his career. And a specific president is less important than the basic beliefs and principles of politics. Which is less important than how democracy works, for example, and whether democracy really is the best form of government, and if not, what is.
Beyond that comes things like what is a good citizen? What is a good human being? Hey, what is a human being?! What's our relationship to the world and the universe? What is my purpose ultimately?
You'll notice these questions become more and more difficult/impossible to give short or simple answers to, and they stretch over more and more time in relevance, and they rise in importance.
Such questions also tend to induce great existential anxiety, which is for real and very uncomfortable, and for this we take pills, or large doses of TV, or Twitter.