Whenfrom a rotation lock to a mute toggle, many iPad owners were displeased. Instead of flicking a simple switch, they had to swipe the screen to the right and then select the screen orientation lock on the screen. This is the same method as used on current iPhones and iPod Touches, so perhaps the idea was to have that same experience on all of Apple's mobile devices. However, I think the need for a mute switch is not as necessary on the iPad, and that a rotation lock was far more useful.
It seems Apple may have listened to its users, for iOS 4.3 will finally bring back the option for a hardware rotation lock with the iPad via a new preference in the Settings menu. Simply choose whether you want the switch to act as a rotation lock or a mute switch, and you're good to go. We don't know too much about what else iOS 4.3 might bring, but this change alone might be worth it for most people to update.