I think the specification committee for ANSI Common Lisp would have agreed that defaults matter. It's just that their criteria for defaults was "What professional programmers are doing right now".

Historically, Scheme somewhat dodged avoided issues like argument order by excluding functionality from the language spec. My experience is that once Scheme gets expanded out and becomes Racket, the many hands show up as inconsistencies among similar functions much like Common Lisp.

Clojure, to me, seems to have the right idea: procedures that abstract operations from data types...for example there is not one mapping procedure for lists and another mapping procedure for arrays. Racket seems to be headed in that direction.