RSS is only really useful as a conversation rate in communities. Take HN for example, it keeps you abreast of recent stories without having to open the page. In news sites, it's even more useful to scan the news. The conversation comes when users opt to partake in discussion.
That said, some sites do it badly, my personal experience of ARS Technica for example. I'll often see an interesting article I want to read, but then see something like "Read the other 52 paragraphs" and decide to come back later at which I never do. There's an art to creating feeds, almost like sales-people that excel at converting window shoppers into actual shoppers due to how they design their shop windows.
That happens when a blog doesn't have a well defined subject. It also happens if they aren't incentivized to go to the website, like when publishing articles in full I prefer my reader since it is consistent.
What I have found is that the few RSS subscribers I have are an excellent distribution channel on Twitter/HN/etc...
Also interesting - RSS (for me anyways) converts really poorly. On 100,000 pageviews, I only pick up about 100 or so RSS subscribers.