We do, we're constantly inventing language. Mathematics is a language and it evolves constantly adding new "words" (axioms, definitions, structures) and new "grammar" (proof techniques). Music is a language, cinema is a language, comic books are a language (with dialects: the "syntax" of manga is different from that of western sequential art, as explained in Understanding Comics)... Not to speak of the fondness of computer scientists with inventing new computer languages.

Keynesianism is intellectually hard, as evidenced by the inability of many trained economists to get it - Paul Krugman