While browsing the web for some Japanese market light fixtures to consider adding to my collection, I have noticed that a good number of light fixtures intended for general lighting often use E17 intermediate base incandescent lamps, CFL lamps, and LED lamps. Why is this so whereas in North America, we sometimes use E17 intermediate base incandescent, CFL, and LED lamps for ceiling fans?

They used intermediate base because it was compact and could handle more watts than candelabra could. In Japan, it is common to have incandescent chandeliers and wall sconces with mini "krypton" lamps that are very high intensity for example a 55w krypton lamp puts out a little more intense light than a standard 60w a19 lamp with the same amount of lumens. Japanese love compact, yet useful items. For example, their transport trucks are smaller than the ones in the USA, their cobrahead streetlamps are quite compact as well as remotely ballasted, and another example is appliances. In Japan since there is not as much land, they had to innovate and engineer things to be compact, yet equivalent to their counterparts made in USA. The downsides to intermediate base incandescent lamps is they can get very hot and not last as long as medium base lamps. But intermediate base socket is more durable than candelabra so replacing lamps often doesn't damage the lamp holder as it might on candelabra.