It would be good if we could access saved .bru files a little more directly by having a 'Library' button along the top in the main menu, rather than the File > Open procedure.
The location of the library would be set in the options, e.g. "J:\UTILITIES\Bulk Rename Utility\Actions" and then all the .bru files in that 'Actions' folder and subfolders would be available from the BRU 'Library' menu button. Any subfolders under 'Actions' would appear as folders in the 'Library' menu as well.
I would still keep the 'Open' button above 'Preview' - but that would be intended for a limited number of your most commonly used .bru files.