This nade is important and useful if one of your mates wanna go short and don't want to be sniped by an AWP at bench. It covers the whole bench and there's no way to peak from bench anymore.

Maybe you cant see the wire, that's because your graphics settings are too low. Try to push the detail settings that you can see it.
And no, there's no way that the CT AWPer at bench can peak over the smoke. It would be only possible with a Second player boosting.
My config's