As an example, I have several vehicles, some personal, some business. I have vehicle related categories and use tags for the specific vehicle. When reviewing annual reports for tax purposes, seeing the vehicle in the tag is a huge help in verifying the information I report to the IRS. Sometimes you see something that you've incorrectly categorized all year and need to go back and correct.
Fyi - my extract_data extension available from my site extracts the tags properly, even on splits, and you can extract to csv and then load into excel - if it helps.. The specific option you want is extract account registers