Riding in rain is like driving in rain. You take account of the road conditions, visibility and so on and then ride accordingly.

As far as traction is concerned, road bike tyres are too narrow to aquaplane, so no worries there on a paved, unpainted surface. In fact slick or slightly textured tyres are better than treaded tyres in the wet because they put more rubber on the road. Look for Crud roadracer plastic fenders/mudguards. On most frames you can just squeeze them in over 23mm tyres and they remove the main penalty of rain riding, which is getting a constant stream of spray up your ass from the rear wheel.

Buy good lights and use them.