Pretty much any extra skill will make you a better programmer if you disregard the time put into learn it, so that's hardly a high bar. What about comparing the marginal return of an hour spent learning C with an hour learning best practices in their own particular field, whatever that might be?
> Most programmers will not need to write code in C. But they'll still be better and more versatile programmers if they know the language.
I agree, although I'm not sure C should be the top priority for someone that will never need to actually use it. There are lots of other things to learn and nowhere near enough time to learn them all.
Although learning C when you already know other languages is not particularly difficult.
That is true. Most programmers will not need to write code in C. But they'll still be better and more versatile programmers if they know the language.