And to @fallenchemist 's point … no knowledge is useless. Even Rocky and Bullwinkle is lots more fun if you know what is the “Ruby Yacht” of Omar Kayyam.
Even - or especially - in engineering, I think the real value added parts are in streamlining old processes and in new invention. Both of these call for clever juxtapositions of existing and original ideas - and the arts regularly confront us with the exactly that.