The other ironic factor is that Google derives revenue from many of these sites in the form of AdSense revenue (or Search Partner Network and Ad Exchange invent

The other ironic factor is that Google derives revenue from many of these sites in the form of AdSense revenue (or Search Partner Network and Ad Exchange inventory). So many intangible factors here. A big one being "does improving the overall search experience by providing the most relevant results in the SERP outweigh the opportunity cost of the lost display revenue?" I wonder how this game will play out though since well-optimized sites tend to be very careful with what they put in the title/metadescription to encourage the click through, and ultimately an entire subset of sites have no incentive to create content if Google starts publishing results that don't necessitate further investigation (ie. clicking through to their site).