1. Be able to view and make comments, where available. - Obviously this is also a restriction of RSS as it currently stands.
2. Control a separate tab in the browser which is automatically redirected to the source of the message currently being viewed. This would have two benefits(?) Firstly it would be much quicker and simpler to go to the original version of a feed item. Something which is common if the feed doesn't contain the whole text, or if wanted to view or add a comment. Secondly, it would provide page impression information for the site owners. OK, so page views might not be totally accurate, but would get more analytics type data than from with a feed.