The conventional wisdom --- or what stands for it in an unconventional and developing digital sphere --- was that full RSS feeds somehow keep people from eventually clicking to your site. Why do so when the full story is before you on a feed?
But the Guardian has opted for the full feed and is asserting the impact isn't harmful. The head of Guardian's development suggests, in fact, that the move will better engage users. It's a bold move and it'll likely prompt others to follow suit.