So, patch 8.14 is here and Riot has decided to give Vi some more CDR and the attack speed she was promised last time they touched her - which got canceled. I suppose they can see that Vi is so weak compared to many other champions for so long now and they just try to play around the CDR to no avail. Yes having a little bit of CDR could be useful, but as I have mentioned many times before, the main problem with Vi is totally different. Her gameplay and kit do not coincide; simply put:
Scenario A: Vi builds raw damage: She becomes a monster for 1v1 duels and wins most of the time but she dies instantly in teamfights accomplishing almost nothing.
Scenario B: Vi builds half tank-half damage: Decent teamfight potential; not much dueling potential; so slow and boring to play.
Scenario C: Vi goes full tank: No dueling potential; gets outscaled by almost everyone; heavily reliant on her team; survives teamfights but doesn't necessarily win them.
**The problem with Vi:** She is designed to charge in and reach the backline but she cant survive there even if she manages to kill the target somehow - considering all the stuns, dashes, shields, heals, etc. and the whole enemy team collapsing on her. It would just be a one for one. Think of other champions that can go with that play style: J4, Camile, Nocturne, etc. Each of them has something to reach the back line and live long enough for their team to follow up. But Vi is just made to go in and... die...
I have already posted on this before and how to alleviate it to some extent but now that Riot is noticing her, it would be better to tackle the real problem not beat around the bush and play with CDR. Her abilites suffer low synergy and work against her.