All jokes aside, you just described literally all the points I encountered while developing the built-in feed reader for HeyHomepage.com Good summary!
One thing I notice a lot of people say - like you - is "forcing users to link through to read the article on the original site (semi defeating the point of subscribing via feedreader)".
I don't really agree and my own approach focuses explicitly on sending visitors to the original site. I only show the snippet, even when the full content is in the feed. Imagine you did your best for your website, made it nice and shiny, you want people to see the site as well. The original site usually contains more content, like a photo or image, which might also be useful for visitors. Besides, I want the webmasters to know I was there by showing up in the visitor statistics (I attach a '&rss_ref=heyhomepage.com' to the end of the link to the original site).
I'm not saying one way is good and the other bad - there are valid reasons for seeing a feed reader more as an aggregator - but I wanted to point out there are valid reasons for doing the opposite as well.