While well-constructed C programs are as minimal and straightforward as programs come, the language is certainly full of pitfalls (just look at the underhanded C contest). Keep in mind that most computer science students in their first intro course have not yet developed the mental models that experienced programmers take for granted. Students will try doing all sorts of things which don't make much sense, and C is overly permissive of these things unless you introduce additional tooling, e.g. valgrind, which can become very overwhelming for intro-to-CS students who are still feeling lost.
I agree that C0 on its own is overly simplistic, but the way it is used at CMU is as 'C with training wheels' - strict type checking, no potentially-unsafe pointers to the stack, dynamic array bounds checking, etc. Then, two thirds into the semester, students transition to real C, and learn how to correctly manage those potential pitfalls.
This is how students at CMU have been learning C since 2010, and graduates don't seem to be any worse off for it.
I agree that C0 on its own is overly simplistic, but the way it is used at CMU is as 'C with training wheels' - strict type checking, no potentially-unsafe pointers to the stack, dynamic array bounds checking, etc. Then, two thirds into the semester, students transition to real C, and learn how to correctly manage those potential pitfalls.
This is how students at CMU have been learning C since 2010, and graduates don't seem to be any worse off for it.