Thank you for an alternative definition. In my opinion adding more data-structures into a Lisp ruins it. It is a List Processing, for John's sake.)
More seriously, having exactly one common data-structure for code and data is what holds everything together, the source of power, compactness, elegance and readability.
A small additional effort, a self-discipline of using lists correctly (remembering the costs) everywhere and using hash-tables and arrays only when absolutely necessary is the way to write decent Lisp code.
In case of Clojure it is just a mess.
