One use of dotted lists is the degenerate case of a dotted pair: (cons 'a 'b). Slightly nicer for representing a pair than a complete list (though less so with the lst.n syntax). But it seems to me like they're important to have because of what a list is. A list has a car and a cdr: (car (cons x y)) -> x, and (cdr (cons x y)) -> y. If you remove dotted lists, you break that valuable identity. Would (cons 'x 'y) be an error, or implicitly create the list '(x y)? Either way, there's inconsistency that will come back to bite you.
