User blog comment:Astanas7/Fixing Skarner: Proposal 24§3c/@comment-1330314-20140215132416/@comment-1330314-20140215185552

does have a perma-slow, which is why it was a huge problem until the rework. Now it has an extremely difficult build path to compensate.

Moving the slow onto Skarner's shield creates a similar degree of binariness: either you break the shield and Skarner loses his CC, either the shield holds and Skarner gets to slow everyone around him for a full 6 seconds. Trading it on Fracture for the movement speed buff would also create weird gameplay issues: you're throwing in a skillshot out of your attack and aura range to get to a target, but you only get sticking power once you walk the remaining 700 units and attack them, where you're already going to be sticking to them. If anything, the current slow on Fracture not only makes it useful, it gives Skarner far better reach.