Comment by tharkun__

FWIW I think that whether someone wants to use mutable objects or swears by immutability should be their choice, especially for interoperability with legacy code. It can be much easier to 'just go with the flow and be careful' in a legacy code base vs trying to have a clear separation of where immutability has been introduced already and where we still don't use it. Not everything is green field (in fact most stuff isn't) and not every company gives you enough time to always Do The Right Thing (TM).

Copying objects is a well known need and there are countless libraries that try to help you with it. All with their own problems, notably runtime errors vs. compile time safety or pervasive use of reflection.