It's usually over-general, periodic, spasmodic even, partial and expensive. But for truly digital publishers the terrain is totally different. Websites have plenty of raw data about their visitors which costs almost nothing to collect. Though the logs are a potential treasurehouse of information, historically they have mostly been used by system administrators for a quick overview of bandwidth problems. The logs would show peak traffic times, which pages are most popular or rarely visited, how the data is flowing back and forth between your webserver and your users.
Many webmasters ignore their logs completely.
Or they take only occasional, cursory glances at them. Others are beginning to move away from the crude macro-level of analysis. And marketing and advertising departments are waking up to the possibilities of using the logs to draw a far more elaborate picture of who their customers are, how they are using the site, and what content they want and expect. They will be at the very heart of the effort to turn websites from mass marketing models into mass customisation ones. You can bet on that.