IMO, RSS feeds have always been kind of cheesy.
They've traditionally had problems with servers unable to serve the content well under heavy load, and if you're launching a browser already -- why aren't you just reading the actual web pages anyway?
RSS seemed like kind of a fad to me when it first took off, and at this point, if you're using it, you may as well use a piece of software designed just to work with the feeds. Pretty sure Apple sees it the same way. Why bother with it when it has little to do with the rest of what a web browser is all about?
Totally opposite view. LOL.
RSS is a very useful technology, but you're right that the browser is not the best place for the aggregator, in my opinion. A dedicated RSS reader has always worked better for me. I never used Safari or Mail's RSS aggregators, as I found them clunky and out of place.