Apart from the Eldar with their insane damage; payoff on torpedoes feels decidedly sub-par, especially when viewed in light on the amount of effort required to actually get off a decent volley.
Compare this to Nova cannons or bombs, where you get much better payoff for substantially less effort expended.
What we need is a better way to tell ships where to fire their torpedoes. So that the player doesn't have to obsessively position ships just to get any sort of value from their torpedoes.
I think that in interface similar to that for High Energy Manoeuver would be a massive improvement. The player would simply indicate what direction they want the ships to fire and then the ships would orient themselves in that direction and fire off the torpedoes without needing any further input from the player.
This would make torpedoes much more convenient to use, especially in larger battles where the player can't see to the precise positioning of single ships.