Who doesn't love filling out Metadata?
It would be very helpful to have a "Metadata Template Manager" window. You could keep track of different metadata templates and apply them across multiple datasets with a single click. Also, having a Tabular view of metadata fields, for a data-entry approach to making quick changes and saving to a new version of the template.
Here the emphasis is on working with massive numbers of files, and being able to quickly make changes to sections of a metadata template to apply to subgroups of files.