So do you think we will ever see a ship with a more narrow firing arc? Instead of a 45 degree angle, (Actually I think it's closer to like 48 degrees, but I digress), perhaps we would see a ship with a 30 degree angle but significantly stronger attack? The idea here is that you have to line up your shots with much less room for error, but the advantage is you get a 4 or possibly even 5 dice main weapon attack.
I think if you went with a 4 attack narrow primary you could manage it somewhat cheap, I'd say in the area of 23 points for the base model (provided it isn't super tanky).