There is cover already there. If you are behind barrels and they use straight shooting range attacks or skills, they can't hit you and you can't hit them. Same goes if you hide behind a huge rock or something. But stuff like barrels are here not indestructible, some are even highly explosive if they get shot with fire. If you are on a higher position you also can retreat from the edge, so they can't shoot you directly.
But with all those displacement skills, more than that would hardly help, because you can just jump/teleport behind your enemie.
