Git was also designed to have a fast, simple back end, with a script based front end. Each command that you're used to using with git is just a shell or perl script that calls a few basic git functions to mess with blobs. Therefore, it is easy to add new tools and scripts. A good example given the darcs context would be: http://raphael.slinckx.net/blog/2007-11-03/git-commit-darcs-...
My point is that the architecture of git allows us to write scripts that work at the same level as the other git scripts; we can keep or leave the others as desired.
