The select widget has evolved tremendously, but it is still lacking some important features like the interactive selection method in ArcMap: add to; remove from; and select from within. In the case where we want to export to csv and need to select multiple areas, we would have to run it multiple times then edit the csv file to add the other records from the other csv. That is a cumbersome workaround to something that feels like it should be built into the widget. Another situation would be where we may want to remove some features that are in the current selection before exporting it to csv, but it wouldn't be possible without the remove from selected feature and the way around that would be having to sift through the csv file to remove the record.
