The real power comes in dumping the issues, wiki, PRs, and any other information that is not completely contained in git. Having something that would dump the git+ so that even if a site like GitHub were to shutdown you at least had data, in hopefully human readable format like JSON, that can be parsed at a later time if you so choose.
This would also open the door for interop between things like GitLab, GitHub, and Bitbucket which all seem to have their own version of what the term "git+" should be. If this could be a pathway to lead to standardizing that API on top of git so that all these different players can talk with one another would be kinda huge as well. It's hard to see Github and Bitbucket wanting to work together for something like this when they have mouths to feed but something tells me "if we build it, they will come."