Some typical uses for scripts are:
To automate a complex series of tasks
To perform custom checks on a schematic
To add a new command to a popup menu
To add a new menu with custom commands that invoke user scripts or command line commands
To build a new dialog box that adds functionality
Perhaps more to the point, you can create scripts that will assist you as you create and test your design. Scripts can:
Provide message boxes that inform you of the status of your project or design
Generate reports, statistics, bills-of-materials, parts lists and other useful data regarding your design
Automate the steps involved with changing design data, adding documentation to the design, or even adding components, nets or other items to the design
Define custom design rule checks