Considering that (1 2 3) is just sugar for (1 . (2 . (3 . nil))) modern lisp programmers find many practical uses for dotted lists.
In this case the implementation and interface are so intertwined that it seems difficult (impossible?) to change one without significantly changing the other. As absz pointed out, car, cdr, cons would have to be rethought and redesigned or simply replaced.
If you get rid of cons/car/cdr I don't think you really have lisp anymore. That's not to say non-lisps are dumb or useless, but when you set out to create a better lisp you should at least create a lisp.
I think that a sequence abstraction, à la Clojure[1,2], is a nice idea though.
