I sometimes wonder if Attack Speed is the real issue with ADC balance.
Whenever an ADC, or the role itself, is strong enough to warp the game, AS always seems to be at the root of the problem.
Critical strikes are strong on their own, but when most of the sources of critical chance actually increase your critical damage output by a deceptively higher amount due to boosting AS as well...
Plus, we have Kog and Varus doing their on-hit thing, which is also an AS-heavy build.
Ranged champions need to have their AS gains controlled somehow, I think. Don't ask me what a good way to do that would be, though.