I also saw (1) be true most of the time. Why isn't Copy / Clone / Immutability the default (pass by value), as opposed to the exception? It seems like if you fo

I also saw (1) be true most of the time. Why isn't Copy / Clone / Immutability the default (pass by value), as opposed to the exception? It seems like if you found this was slow, you could go back and fix things when you need the performance, as opposed to wasting time doing lots of copy / clones (and really ugly code). How does binding all sorts of short-lived variables make your architecture better?