“Including more content increases subscribers, which in turn increases the number of impressions you serve into your feed. Though you might think this will reduce clicks to your site, our experience has shown this isn’t always the case. Often, the audience reading your feed is a separate audience from those who visit your site, so we encourage you to monetize your audience of feed readers separately.” — Says Google. The monetary aspect of it is one thing, but the separation of your audience is the bigger issue, IMO.