All I ever see in the logs is "http://pagead2.googlesyndication.com/..."
*sometimes* the link will show me the ad but never the page it is on.
Why is this? Being blind it makes it hard to determine value other than conversions (in the agregate only!) , and that is not enough (for me).
Cause google (and rightly so) doesn't want you to cut out the middleman.
Maybe, but the whole concept of AdSense is keyword or page-targeted advertising. Unless a publisher's site has an extremely narrow focus, it isn't practical for the publisher to negotiate directly with advertisers for every keyword or page topic. Just as important, it isn't practical for advertisers to make individual deals with a large number of publishers.
Google's role as a middleman goes beyond ad sales. Google is aggregating content sites for advertisers and, at the same time, is helping publishers monetize pages that otherwise might not produce revenue. As a publisher, I'd have no interest in bypassing the middleman, and I suspect that most AdSense advertisers wouldn't, either.