It's worth contemplating that Linus doesn't hang around defending git. He put it out there -- bless him -- and let it take on its own life. And its destiny is up to us.
git doesn't need to be taken out of the command line. That's where its true power lies, as with all *nix tools. The fact that github can do so much with it is because of this feature, not because they are changing it. That's a powerful thing, and a testament to Linus' design of git.
I bet Linus never envisioned github when building git. And that something so revolutionary -- and I do think github is revolutionary, albeit for a niche of geeks -- should come out of such a development is testament of git's design.
Sure it's a hard package to master -- I haven't -- but whatever you want, and a lot more, is there if you need it. And no-one yet, to my knowledge, has complained that git killed their project.