There should be some kind of logging utility part of Phobos. I know there used to be one and it has been removed, but it doesn't have to be as complex as that one. There should just be an alternative to the standard output which allows you to set a log level and add listeners.
I was thinking of maybe a Object Oriented class that basically works as a plugin server, and when you log a message to it it'll call all its listeners (listening to that log level) which then log the message. This'd provide a minimal structure, easy to maintain, yet very flexible / expandable and easy in use.