C language is as simple as it gets. The only concept people struggle with is pointers, but even that is a very simple concept. Teaching something that is simpler than C to computer scientists will breed very poor engineers.
I believe it is "simpler" in terms of formal semantics. Formalizing standard C is way harder (see https://github.com/kframework/c-semantics).
In fact, C0 is explicitly targeted at computer scientists rather than engineers.