There are so many competing concerns to handle -- prioritization with a source, prioritization between sources, discoverability, UX flow, preview vs. full content, social content from your friends vs. institutional content, commenting, and last but not least, a business model: what is incentivizing content sources to cooperate in good faith and not ignore it or abuse it?
Fact of the matter is, RSS is just far too simplistic to handle these competing concerns in any kind of balanced or reasonable way. But it's also possible there is no single answer.
Which is why different "newsfeeds" for me (HN, Reddit, NYT, AV Club, Twitter) have drastically different interfaces and interaction models. I don't want my HN to work like Twitter, or my Twitter to work like the NYT. And I can't even imagine of any possible interface that could somehow aggregate them all.