Maybe I'm just being paranoid, and maybe it's not much different from a table or floor lamp, but I'm thinking about the hazard of foreign objects falling into an empty socket.
Back in college they had bare porcelin lampholders mounted on the walls in the stairwells in the dorms. Bulb up position. Sooner or later a student needs to replace a burnt out light bulb in his desk lamp late at night, so the easiest thing to do is steal a bulb from the stairway. And some students didn't bother to install the dead bulb in its place. Later on some fool decides it's great fun to make some sparks by dropping a penny into the upwards facing empty lampholder that still has power on it...
Later on the college replaced all those lampholders with something indestructable, something likely used in jails...
[This message has been edited by wa2ise (edited 02-24-2006).]