I develop a lot of Excel add-ins. My philosophy is that an add-in file should be as small as possible.
Smaller files load faster and take up less disk space and memory.
When I first started using Excel VBA, I was surprised to discover that Excel does not strip out your comments when you create an add-in from a workbook. As I gained more experience with VBA, I noticed that some workbooks increased in size for no apparent reason. This is especially true for workbooks that contain VBA code that goes through lots of revisions. The reason is that Excel does not do a very good job cleaning up its symbol table - which is stored in the workbook file. Save the workbook, and note the size of the file.