But they don't do "exactly the same thing, with the only difference being..." unless you ignore the index, which is one of the extremely powerful abstractions that sets git apart. Sure, git could expose a simplified lowest-common-denominator interface that plasters over its differences, but the same interface would (and gitless does) plaster over its strengths and encourage people not to learn them.
I agree with TFA: this isn't a UI issue, it's an abstraction issue. Several of git's abstractions only make cost/benefit sense in a distributed environment. Unbundling the cost of learning dVCS abstractions would make git a better fit for the Cathedral and a worse fit for the Bazaar. This might be what you want, but you should at least be able to understand why other people do not want it.
They don't do the same thing implementation wise, but they do the same thing ux wise. This difference causes all discussions like the above: it seems as if some people like ux "plaster", while others like bare-metal tools.
They only do the same thing if you haven't previously used `git add`. If you have, `git checkout` will use the contents of the index, not the contents of the last commit.
I agree with TFA: this isn't a UI issue, it's an abstraction issue. Several of git's abstractions only make cost/benefit sense in a distributed environment. Unbundling the cost of learning dVCS abstractions would make git a better fit for the Cathedral and a worse fit for the Bazaar. This might be what you want, but you should at least be able to understand why other people do not want it.