Why would anyone pick Warwick...
... when Vi was available? Honestly, their kits are very similar but ALL of Vi's abilities are better than Warwicks. Warwick has 1 damage ability. Vi has 3. Their ults are single target lockdowns, but Vi's is much better. Warwick has lifesteal, but doesn't make him as tanky as Vi. Vi can even gank better pre 6. I can't think of any area where he is better than her except maybe for the first clear in the jungle.
Either Vi needs nerfing or WW needs some love. I think they should rework his passive and E by switching them. WW passive could let him know when low health enemies are nearby and speed up his pursuit to them and his E could be lifesteal that he can level up.
I would like to hear if anyone thinks this assessment is right.