What is Google's motivation?

Was reading this article on who is actually clicking on ads and it got me thinking about something slightly problematic: Google doesn't have any real motivation for improving search results because the worse the results are, the more likely you are to click on the ads. Obviously this is oversimplified, but it's not something I'd thought of before. While I'm on the topic of questionable Google motivation, I really don't agree with their paid link policy. Call me crazy, but I don't see the difference between a paid link and a non-paid one and overall it screams to me of Google squashing AdSense competition. Pete made some good points on this. (For the record, I think this needs to be a full entry.)