I'm very curious; what are their practical purpose? I've never seen them used before, but I'm not sure what advantage they're supposed to confer over SNACs or Novas.
They use less energy. I suppose you could develop some sort of strategy where certain ships in your wing are primarily focused on de-shielding the target while others do the hull damage, but in my experience it's far easier to just use SNAC and Novas.
As you noticed, they are useless. They were meant to be alternative to deshielding caps and gunboats but they are not doing any better than any other bomber weapon.