ed, I know what you mean -- it seems like an empty argument until you get one of these phones (specifically Android) with the fundamental buttons all touch sensitive.
Normal touch-screen phones all have context sensitive operations, for example you are playing a game and no where on the screen can you accidentally press the "Fart noise" app button or the "Hangup" button -- because they just aren't there.
With Android there are those 4 or so required buttons (Home, Back, Menu, Call/Search) and moving them from mechanical buttons to capacitive you CAN find yourself in the middle of a YouTube movie or game where your thumb just barely touches the back button, closing the app and taking you home.
Or as another user mentioned, you are on the phone talking and part of your chin or face (if you try and neck-cradle the phone while doing something) may hit the hangup button, menu button or Home button to suddenly start activating other things on the phone, ending or interrupting your call.
It is absolutely MADDENING.
The iPhone never suffered from this because it always had the one single mechanical button and the proximity sensor was good enough that when it got close enough to your face, all input on the pad was deactivated. Most of the Android phones that have mechanical core buttons don't suffer from this either for the same reasons.
It's once you get those damn touch-sensitive buttons on there... oh boy, there are a few times a week where you just want to throw your phone right into the ground and wish it a happy birthday.