For what it's worth, I like them primarily because I don't mind using proto-generated objects as pieces passed around the stack (at least at higher levels of th

For what it's worth, I like them primarily because I don't mind using proto-generated objects as pieces passed around the stack (at least at higher levels of the stack). I lose consistency if I can do that for some objects, but am required to convert objects if they would need a mapping type. It follows sorta the same reason that Clojure became a fairly widely used lisp – mapping types are extremely common in real world programs. Having them supported first class makes a lot of common tasks quicker to get through.