Islands of talent in a foam-flecked sea...
Well I could make great arguments about the 'common's and the principles of web 2,0 (user interactivity as a concept is not new, merely rebranded - rebranding being the very essence of the whole web 2 phenomena) but I will simply resort to two arguments.
The first being that the web allows the rapid disseminaton of new information, for good or for ill, and the equally rapid analysis of such information by a wide variety of specialists - and yes, such specialists do exist out there. This is not a new thing. The minute the web became accessible to the general population, such thing were possible.
The second being that the argument put forth by nick cohen is a classic example of the mote and the beam. When 'proper' journalism is capable of producing high quality output 24/7 without any of the dross, sensationalism, ignorance, bias, deception, 'massaging' of statistics, twisting of events, ignoring of facts and outright lies promulgated by the vast majority of journalists, then they will be entirely justified in their criticism of the 'blogosphere'.
The simple facts are that I can pick up a copy of any major newspaper, pick a story and then go and find detailed analysis of that story on the web from a dozen experts (and a few hundred idiots, it has to be said, but how different is that from the print and TV media, really? Jack Thompson anyone?). I can find stories covered on the web that the major media simply ignore because, they say, it's not newsworthy, or for whatever other reasons they offer, yet at the same time they wonder why their audiences are disappearing. I can also find stories that don't deserve to appear in any shape or form in both print and on the web, yet unsurprisingly do appear in both.
The only difference between the print media and the web is that the low start-up costs of web publishing allow more people to get going. The signal to noise ratio is probably identical.