No matter which destruction spell you dual cast (with both hands), it puts the graphic right in front of the reticule, obscuring it. I some of you are thinking "it's in the middle of the screen, that's where you want the spell to go". But mobs in the distance, are smaller. If they are moving, you can't see when they are no longer right in front of you (which happens in a split-second), because the big fire/frost/lightning spell ball you just created is blocking sight of anything else behind it.
You don't have this problem with bows. Why can't you just hold your hands waist level and cast a spell, so you can see the reticule on the mob. You don't really have to bring it up to your eyes do you? Maybe a perk, down the tree a little bit?