Google Reader's page tracking feature was useful to monitor the web pages that don't have feeds. For example, you could use it to find when Google changes the privacy policy, when Google Chrome adds new extension APIs or when there are new products in the Google Store.
Unfortunately, Google Reader's feeds looked terrible. The title for each item was "generated feed for [URL]", the feature didn't detect new images and the feeds were updated when the new versions of the pages were added to Google's search index. Here's Google Reader's feed for google.com and here are the changes found by Page2RSS. Page2RSS found 8 changes in September, while Google only found one. Page2RSS has another important advantage: the service constantly monitors web pages and it's not tied to a search engine that indexes billions of web pages.