people aren't leaving your site because they don't find your site intersting...they are leaving your site because they see a link that looks interesting as well. They are on your site because they are intersted in your content in the first place. The key is to get that same visitor back over and over again...not nec. clicking your ads over and over again, that wouldn't be idea for obvious reasons...but visiting your site for the content and supporting it by clicking ads.
It's a good point. There must be a balance between the content and the ads in my opinion. Serve quality content, you will get quality ads, and therefore more clicks. (in most cases)