Why learn C? (O'Reilly Radar)

While he already mentions the simplicity of the language as a plus, I think that this point can hardly be over-stated for didactical purposes: In a typical course you have half a year to teach one random language to a bunch of students who may not have done any programming before (and some may not be going to after).

With C I found it possible to make the presentation "complete" in the sense that it really covers all logical and syntactical aspects of the language, so students should "in principle" be able to understand almost any code in C at the operational level. (It is of course impossible to teach sane software design within the same single course).

There are good arguments to prefer other languages that make students more productive quicker (found python to be good in this regard), but I found that this inevitably leaves a lot more loose ends (in the sense of: "there is something going on behind the scenes that we have no time to talk about").