The "curated package sets" on PyPI idea sounds a bit like Steam's curator lists, which I like to think of as Twitter for game reviews. You can follow a curator to see their comments on particular games, and the most popular curators have their comments appear on the actual listings too.
Might be interesting to see how something like that worked for PyPI, though the initial investment is pretty high. (It doesn't solve the coherent bundle problem either, just the discovery of good libraries problem.)