[Please forgive my top posting.]
I think C is not taught as much in universities these days because the
emphasis is on languages with native object orientation. C# is, indeed,
good for vocational reasons, but many also consider it worth teaching as
a language with a superior design than Java, which, in turn, is superior
to C++. These languages naturally learned from their predecessors and
improved on them in significant ways.
I agree that it would be beneficial to Ruby development if I already
knew C. I did not study computer science in college, however, and have
picked up higher level languages as my interest in programming grew.
Technically, C may not be strongly typed, but it does require variable
declarations, memory management, etc., which is the kind of low-level
programming I want to avoid. At this point, I think I can contribute
more by application development with Ruby than by learning C to improve
the language, itself.