There is one thing that can be more frustrating than accidentally entering the wrong password. That is to have to wait to enter it again. The iPhone is disabled screen appears after too many password attempts. One would expect to see an error message after making a password entry mistake but what is the point of temporarily disabling the device? If you know the correct pass code you should be able to enter it. If you don’t know what it is you should make an attempt to find out what it is? Too many attempts should wipe the data on your phone at the worst. What is the purpose of displaying a big red stripe that says iphone is disabled?
There are few situations where the iphone is disabled screen would benefit the iPhones owner. If for some reason your iPhone was left unattended and your password was enabled then it might serve to prevent someone from discreetly attempting to guess what your code is. One has to assume that this other party is honest enough not to simply steal your phone. So it appears that Apples motivation behind the iphone is disabled screen was to protect you from the people that you encounter who might want to spy on you.
Another situation that often causes the iPhone is disabled screen is when your device malfunctions. A digitizer which responds incorrectly can make entering your password difficult. Since the touch panel on your iPhone sends the wrong signals to the phones processor, it may take several trials to determine where you must touch in order to get the proper response. When this happens you will encounter increasingly long interruptions from the iPhone is disabled screen.