I've been wanting to disable the vibration of the alarm for a long time and found no easy solution. Before my iPhone 5, I kept my iPhone 4S in a dock to play music through/charge it and the phone vibrating in the mornings didn't help me. It's not like I could feel it going off, so what's the point? After a while the damn vibrating got more annoying than the alarm itself. How many people sleep with their phones to the point having the alarm vibrate would be USEFUL?
At least give us a separate option to disable vibration on alarm only, without having to turn it off system-wide.