I never made the transition from Doom and Duke Nukem 3D, except adding a mouse (which I did later in Duke3D anyway). I've always played with arrows, WASD has always felt wrong to me, and yep, I'm right handed. I've tried to get into WASD a few times, but using the arrows just seems more comfy and logical, i.e Up is Up, rather than W is Up. That'd be like using the gear stick to steer a car instead of the steering wheel. I think it's comfy too, I have my whole arm rested on the desk, it's nice and relaxing while blowing chunks out of things, and it feels different enough to typing to make the game feel more like gaming.
That's just what I think anyway, each to their own, but the choice should always be given. I know there's other keyboard setups people use too, so that's why it's good to have custom controls.