This idea has a lot of potential, especially if you were to focus on a few situations that I've seen over and over in the corporate world.
The most common scenario I've seen is data coming in an extract format like CSV, containing information required for another business process. You've got data coming from an expense reporting web app that needs to processed before entries can be made into an accounting system. A spreadsheet or database is created by a computer-savvy manager, and a clerk uses it on a weekly basis to do their work of posting entries. If the data format changes, the manager tweaks macros and formulas to adjust, and life goes on. Any new clerks coming on board learn how to use "the spreadsheet" and the business process keeps chugging along. Change managers, and 9 times out of 10, a lack of documentation and knowledge transfer will cause things to blow up in a short period of time.
If you were to introduce a tool that exposes the funky macros and formulas in a more visual, understandable fashion, I think it becomes more easily maintainable. Providing some data validation, error handling and notifications would be valuable. Finally, provide some version control to prevent accidental deletion or modification of important functions. The key would be a much better user experience than the Excel function editor.
