> To a beginner who is used to ordinary imperative languages, that Ruby line is extremely difficult to understand.

I don't understand this argument. You are a beginner only for a tiny fraction of your time using a given programming language. Why are we optimizing a programming language for people who don't know it, instead of optimizing it for people who actually program in it?

> Why are we optimizing a programming language for people who don't know it, instead of optimizing it for people who actually program in it?

Everyone who actually programs in a language was once a person who didn't know it. Languages which optimize for succinct terseness might be powerful once you master them, but they will never enter mainstream use, which I guess is not necessarily the aim.