You get Sneak Attack damage if your Rogue can be hidden during combat. I usually have Astarion jump behind the enemy, Hide, and then Sneak Attack XD.
With how amazing Astarion is in combat, I don't agree with the OP at all XD! Astarion is the best party member in combat, so I can't believe Rogues are weak or bad :P.
It is not that they are weak or bad, they are lacking core features. Their more defining feature, Cunning action, was butchered and everyone has bonus actions.
