Default arguments to anonymous functions are x, y, and z. You can also name arguments like this. {[foo; bar] foo+bar} is the same as {x+y}

I'm not denying it is probably more possible to gain a superficial understanding of what code written in other languages does than code written in k to someone who's never seen k before. This just doesn't seem like that important of a language feature. The 'confusion and extra complexity' you mention wouldn't really confuse anyone who'd tried k for more than a couple of hours (at most).