At times, they would prefer to click a button that says "Print ABC", or "Print XYZ" report, instead of having to crawl all over the huge spreadsheet(and get "lost" every now and then), to highlight and print different report pages. Using a custom built data entry form to make data entries into 14 different cells in different parts of a table(at the same time/with one click) would, for them, be "heaven" compared to making the entries one at a time.
In addition, visualise it having dynamic query/report drop menu interfaces, and a variety of custom buttons: for navigation(within and between worksheets), printing, data export (as PDF documents or spreadsheet files), saving, auto_data filtering, auto_charts plotting, auto_backup of files, user login authentication (for documents with sensitive or confidential content) etc.
2. Sourcing Capital _ For Expansion or Startup. You can make it easier for banks and prospective investors to back you financially and/or take the decision to buy into your business. Those already running their businesses will know that banks like to see detailed business records that show in real terms all aspects of a business' performance. Without detailed and comprehensive spreadsheet tracking, it might be difficult to show this. Agreed there are software applications that capture most of these. However, sometimes, you want to highlight certain scenarios or trends in a way that an off_the_shelf application cannot accommodate due to the uniqueness of your need. It is in this regard that the use of spreadsheet tracking becomes relevant.
You can choose to learn how to do it yourself _ or call in someone(an Excel VB Solutions Developer for instance) who knows how. Again, this would be dependent on your purpose, how proficient you are, and/or how much time you have at your disposal. Ultimately, even if someone develops a custom application for you, it should happen with YOUR guidance at every point to ensure that it does EXACTLY what you want it to do, and that you can easily _ with your developer's support/coaching _ learn how to make modifications to it in future, without needing to call back your developer.