Though I agree with the notion of greater community engagement, please keep in mind that a callback is non intrusive and does not harm the workflow of a page in any way. And most additions that have been made will only work if you actually link e.g. the contacts package and the .LRN instance (so it is not possible for functionality to pop up suddenly out of nowhere). At least this is how nearly all our callback implementations have been designed.
Common standards should include e.g. a callback after a creation of an object.
