Report builders often start out with a data table with as many fields as they can think of. When a report becomes stable it is useful to be able to easily identify the fields that are actually used in the report visualisations and transformations.
It would be great to have an overview of actualy used fields added to the data canvas, which then can be used to prune the InfoLink / Data Connection.
Possibly this list could also be used to query a metadata tool like Apgar built on EBX to include the relevan metadata in your report.
(excluding the table visualisation of course...)