Just seeing this issue for myself with an Elec secondary Tanker.
The problem, as I see it, is that while getting more than one enemy in the really small cones (Jacob's Ladder and Shatter in particular) is doable by targeting one enemy "through" another, it's inconsistent and hard to position, with the enemies often wheeling around each other and foiling your efforts. Hitting two enemies side-by-side next to you is impossible though, because the cone is too narrow to get both when the game insists on having you target one of them, rather than a space in between them. For this reason alone, the cones should all be wide enough to hit 2-3 enemies positioned adjacently around your character at melee range instead of requiring repeated position finagling to actually make the multi-hit power... multi-hit.