Not every computer user should have access to every software capability. Your system can be more stable and consistent when you limit user access to control panel functions, network resources, and other sensitive areas.
Once you have everything set up the way you want it, you can share the computer and rest easy. Any changes a user might make to the configuration or hard disk can be undone by simply restarting the machine.
Interesting to see how well it works in an SBS environment, but if it does then it could be very handy.