Your main priority is to chain torturers as fast as possible. Possibly with a ghost ship involved, but I'm not convinced its much better than another torurer. I mean, if they know you have GS, they should just discard to the first torturer, and then GS will not hurt that much. I think I'd rather just have the extra card, so that its easier to chain.
Play Torturer. Opponent discards to 3 cards.
Play Torturer. Opponent gains Curse in hand (if he discards down to 1 card, his turn is dead anyway).
Play Ghost Ship. What's he going to do? He has 4 cards in hand, one of which is a Curse, and so he has to put something back on top of his deck.
Or say that you played 3 Torturers previously: opponent gains Curse in hand, discards down to 4 cards, and then gains another Curse. You're still forcing him to put something bad back on top of his deck with a Ghost Ship.
Or say that you opponent has a Trading Post (or any other card that trashes multiple cards) in hand, so you play 2 Torturers and he just takes the Curses because he's going to trash them anyway. Normally he'll still have a decent turn, but if you Ghost Ship him after the Torturers are done, he has to pick between trashing and buying something.
You don't even have to play Ghost Ship at the end of a chain; if you know that your opponent put back a Curse on his previous turn, you can start out with a Ghost Ship to bring him down the 3 cards in hand and then start your Torturer chain from there. Heck, you could have a second Ghost Ship that you play after the Torturers.
tl;dr handsize attacks in tandem with Torturer chains are powerful and not at all redundant.
Also disagree with skipping the Bishop. VP chips are important in a game that's likely to 3-pile (Torturer, Curse, NV) and NV doesn't draw very well, plus as pointed out Ghost Ship doesn't draw very well either, so trashing is desirable. Bishop also soft counters Torturer if your opponent doesn't kill your handsize some other way.