We last talked about this quite a while ago. Conclusion was we should use and rely on defaults in Java but at the same time we would also like defaults in schema so they show up as part of context sensitive help and give the user (while configuring) information about default mule behavior without having to go read documentation/javadoc etc.
If we do have defaults in schema, we already do in some places but not across the board we need to ensure they match what is in code. Someone suggested recently having a Defaults class with static final values in per module in order to make this task easier.
AC says this would be most effectively implemented using JDK 5 annotations which are out of scope for 2.0
Currently, the default values are specified in Java, the schema contain almost no default values.