"One hosting author might prefer getters and setters and the other mutators"- A setter is a mutator?as it mutates the value?

Anyway I think the solution is sometimes to write code that works both ways.That is make some subs handle being called on objects with and without any attributes. So you then have the option of passing object or parameters.

Interfaces are used to connect otherwise unrelated classes and don't contain any real code. Thus you separate the actual implementation from the externaly used interface.

The same wrapping/implementation hiding can be done in Perl, except you cannot ensure the classes always implement the required methods for the interface and it is less easy to restrict class access to private attributes.

CPAN modules having multiple interface classes to allow easy implementation/version changes is an interesting idea.