Except that the most cited abuse cases, like with Guinsoo's, have been on melee champions - not ADCs.
There are two ranged champions that make good use of the effect right now: Kayle and Kog'maw. Kayle's strong with it but not overbearing, since she's actually weak before she has a few completed items and her gank potential isn't anything to write home about. Even without the phantom passive, she'd still take it, because attack speed and on-hit damage is literally how she builds. Kog'maw can be terrifying, but he also needs several supporting AS items to make full use of it and he still has the Kog'maw vulnerabilities (squishy, no CC, no escapes) that make it possible to stop him.
Melee champions, on the other hand, have been a giant mess. Shyvana, Xin Zhao, Mastery Yi, hell, even Udyr... all of them have been demolishing people with two damage items and a full suite of tank gear.
I think the current plan (turning SD into flat on-hit physical and moving the proc passive to guinsoo's) is a good one, and will help even the playing field somewhat. My main concern is that they'll render tanks irrelevant, because doing 9% of the target's current health and 4.5% of the target's maximum health in physical damage on average per hit is alarming.