This WSJ editorial makes the case against blogs. In a nutshell:
The right now is partially a function of technology, which makes instantaneity possible, and also a function of a culture that valorizes the up-to-the-minute above all else. But there is no inherent virtue to instantaneity. Traditional daily reporting--the news--already rushes ahead at a pretty good clip, breakneck even, and suffers for it. On the Internet all this is accelerated.
The blogs must be timely if they are to influence politics. This element--heres my opinion--is necessarily modified and partly determined by the right now. Instant response, with not even a day of delay, impairs rigor. It is also a coagulant for orthodoxies. We rarely encounter sustained or systematic blog thought--instead, panics and manias; endless rehearsings of arguments put forward elsewhere; and a tendency to substitute ideology for cognition. The participatory Internet, in combination with the hyperlink, which allows sites to interrelate, appears to encourage mobs and mob behavior.
In other words, blogs are worse, even, than the network news, which at least has editors. While Id love to return to a time when the only people writing on "current events" were Thucydides and Xenophon, Ill take blogs for what they are--in some cases, a more or less thoughtful reaction to the days news, keeping those who report it a little more on their toes. Some bloggers are like editors themselves, calling our attention to and commenting on an array of stories and opinion pieces. There is, of course, a lot of junk out there, but anyone can ignore it, as most ignore this.