How useful are attack trend resources?

The number of virus and worm reports and security bulletins documenting these trends has multiplied. However, despite all this information, does anyone actually know how many vulnerabilities and attacks truly exist? Analysts who follow these trends say that the rise in reports is simply due to more people monitoring networks for vulnerabilities. Other causes are the recent, rapid expansion in "always on" broadband access on devices used by unsophisticated users at the very edge of the network, and the automated tools that malware creators use to take advantage of these often unguarded connections.