I do not think that intentionally making a champion pretty useless until they pass a certain level is a good champion design. The idea that you should hold on till you reach level 16 leaves the champion very boring to play in the first 20 minutes. Especially since you have to run in like a glasscannon before 11 into every teamfight, dealing very minor damage with your autoattacks. IF you dont want to die, you gotta stay at range waiting with 2 fairly low damage abilities. So until level 16 you wait in the backline to ult their key target.