User blog comment:Deshiba/No counterplay/@comment-1330314-20140515231813/@comment-1330314-20140516220725

Reworks take a long time to do, and unless there's a specific reason for holding them back, it's usually preferable to release them as soon as they're considered done. There's no real point to reworking every perma-slow champion at the same time, since they all occupy different niches and perma-slow just happens to be a connecting theme for them. Removing perma-slow from one champion won't affect the pick or success rates of any other champion with perma-slow. Fighters, on the other hand, are a different problem: they're overpowered, and all of them are going to get toned down to the point where they become manageable, but they're all getting their nerfs/reworks released at the same time because otherwise the nerfed champions would be ignored completely as the not-yet-nerfed fighters would become overpicked.

It's okay for Warwick to have a skillshot ultimate and for Vi to have a targeted ultimate because their kits and playstyles are fundamentally different. Reworked Warwick has far more CC, sustain, utility, and potentially even mobility than Vi, and even if he misses his ultimate can still perform an extremely powerful teamfight initiation. He's also a drain tank, meaning that he becomes more effective over time, whereas Vi is a hard initiator, whose burst of effectiveness happens within the first five seconds of a fight. Warwick can afford to miss his ultimate because he can become unstoppable as a fight goes on regardless. Vi, and most other initiators, can't afford to have their ultimates blocked, dodged or interrupted, because otherwise there's not much they can do to influence a teamfight other than deal damage or soak up some themselves.

The issue with Kass's rework isn't that it's making or  overpicked specifically (they're not the only two AP assassins out there). A few red posts indicated that Riot was working on both of these champions nonetheless, and that each of them poses specific issues that will make the reworking process difficult (Nidalee needs a major power shift, Leblanc's lack of counterplay is closely tied to her identity).