Japanese love taking pictures and traveling, so the selfie stick fever was inevitable. Such is the massive use of selfie sticks in the touristic points of the country, that this lead to the prohibition of its use. Mostly in the train stations, due to security reasons, but also in touristic places such temples where massive amounts of tourists can be passing by every day.
People using selfie sticks get distracted of their environment (not a good thing to do in a train station) and also some people tend to do quite stupidly risky pictures. Wikipedia has a list of selfie-related injuries and deaths and the campaign #SelfieToDieFor is aimed to create awareness of the risks of some selfies. So I wouldn’t say Japanese are crazy for banning it, and of course, we love their signs 🙂