IMHO the real key of message passing is localized decision making on a specific instance of data. Similarly message passing allows an actor to decide how to re

IMHO the real key of message passing is localized decision making on a specific instance of data. Similarly message passing allows an actor to decide how to respond to an event, to forward a message, to ignore it, etc. That's possible but more difficult to achieve with Java/C++ "straightjacket" style OOP. Important patterns for GUIs like the Observer pattern are just simpler with a message passing paradigm.