Why not Atom-powered repositories?

Curation of digital projects and media seems to be in my future. I'm not a repository critter of any kind, and have much to learn, but I know for certain what kind of architecture I want to use. Take the indexable, mashable feed (Atom, naturally) representations of collections that Leslie Carr writes about, pair with upload of Atom-wrapped items to the same collections ala SWORD, and then add hypertext-constrained methods for item and metadata modification and deletion. In a word: AtomPub. Less like EPrints, DSpace, or Fedora; more like Google's data APIs, more like what Peter Keane is doing with DASe. Why not?