One user at a time : In the instance where there are a number of people required to work on a spreadsheet, they can only access it when no-one else is working on it.
Not dynamic : Data ranges become redundant when new records are added, resulting in established formulae needing to be altered. Overlooking these errors can be embarrassing and downright expensive, especially if important decisions are being made based on the data.
Protection of formulae : How often have you forgotten to protect the cell contains the formula that took you hours to test and perfect. It takes one instance of honest human error, and that formula is gone.
You can build a reputation as an expert spreadsheet developer. This certainly doesn't hurt the resume. Using Excelville.com to sell spreadsheets allows you to set up a profile with your work, biography, and other info that certainly makes for good conversation material during interviews.
uses of spreadsheet
what is a spreadsheet used for
types of spreadsheet