At least on iOS the company can dictate the security requirements of the device using Exchange. For example because of corporate policies my iOS device is set to wipe itself after 4 invalid passwords have been entered rather than the default 10.
Lets add it doesn't add really any value to actual security. All it does is tick off the userbase and show you as an "unfriendly" security department. Just absolutely silly and whoever implemented that policy should be fired.
