I do think that git's UI is a good case study on how not to design a command line interface. It's improved over the years but I remember that a decade ago the contrast was stark if you compared, say, mercurial to git.

Git always felt more like you were exposed a raw low level API on the command line with a few shell macros on top to make it a bit more palatable which is effectively what it was for a long time. I suppose it fits well within the unix philosophy of clunky but very flexible and not very opinionated tools.