This helps to support custom auditing in cases where the existing auditing needs to be enhanced.
So the idea is that a designer may refactor the audit and create their own logging structures that may not match the auditing output's format.
For example, I often wire up an Execute SQL or Script task in the Post-Execute event handler of my data flow tasks to persist metadata about the data flow.
Currently only a subset of the values currently part of the auditing output are supported for mapping to variables on the component’s Auditing tab.
Example: missing “Time First Existing Dimension Row Received”.