Boxy WC1 ships? What are you people on?
The Scimitar's top things and wingtips are curvy, as are the Raptor's main 4 wings and the two side panels and the cockpit, as are the Rapier's main 2 wings, folded-down wingtip things, side-of-the-cockpit fins and cockpit, as are the Hornet's wingtips and rear protrusions on the wings. Then there's the Drayman, the Exeter, the Dorkir, the Ralari's and the Krant's wings, the Dralthi, the Salthi, and the Jalthi.
A Raptor with it's 4 curvy wings, bubble-like cockpit, and the two arc-like panels is much closer to a Sabre than to a Thud (take 3 boxes, move some vertices, extrude 7 faces) or a Longbow (take 1 box, move some vertices, extrude 6 faces).
If you ask me, the Sabre is boxier than the Raptor, even - apart from the airplane nose, the cockpit, the two nose-mounted fins, and the guns, most of which have minor impact on the ship's shape... as opposed to stuff like the Raptor's panels and big curved-back wings which are the ships most recognizable features.