I am not sure why presenting an aggregator’s output in reverse-chronological order is the best way to do things.

RSS readers that work like Usenet readers are a waste of time, imho. Aggregators should not organize news by where items came from, just present the news in reverse chronologic order.

Actually, Radio’s aggregator doesn’t present the news in reverse-chronological order either: it presents it in reverse-chronological order ordered by feed. And while the reverse-chronological view may be useful, I am not convinced it is the only show in town. In particular, Radio’s implementation gives me information overload because the News Page bloats massively as I cross about 30 frequently updated or verbose subscriptions. IMHO Syndirella had a much better interface: no-frills, highly keyboard-friendly and geared to minimize visual overload.