CV is actually about the same as it was before in S1. The problem is Meta shifts to more aggressive bot lanes and more vision options, as well as Jungle changes (Which make it harder to follow the jungle and less predictable.)
The problem isn't that CV is useless, the issue is that Exaust is FAR more useful in both protecting your carry from kills, and helping secure kills. If we ever went back to the "Farm bot for 20 minutes then carry" meta for ADCs CV might see more use. But since all the sustain supports have been nerfed pretty hard, that might not happen.
Remember remember... the 30th of November. The day that heroes could not save the world. ~In remembrance of City of Heroes.
Back in S1 I literally took it on everyone, no matter where I went. It saved my ass countless times. But having a 20s cooldown was pretty ridiculous. You could use it at the start of the game, and then again when you got to lane.