The current incarnation relies heavily on versioned content. There seem to be more and more package types coming up that don't have a solid way of tracking versions. The biggest issue revolves around discovery on the plugin side. It's not as bad for the user to manage versions on the server side as a way of indicating to other users which file comes after another, but on discovery, there are many types of packages that don't have the version information discernable from the package itself.